fix(eps_bank_name): send eps supported bank names inside the structs for sdk.

## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [x] Bugfix
- [ ] New feature
- [ ] Enhancement
- [ ] Refactoring
- [ ] Dependency updates
- [ ] Documentation
- [ ] CI/CD

## Description
<!-- Describe your changes in detail -->

Previously the bank names were hard coded but we needed to read form `{config}.toml` files to send the supported banks inside `user_bank_options`  

## Depricating bank list on top level of `ResponsePaymentMethodTypes` as we need to send it inside particular required fields .

```rust
pub struct ResponsePaymentMethodTypes {
    /// The payment method type enabled
    #[schema(example = "klarna", value_type = PaymentMethodType)]
    pub payment_method_type: api_enums::PaymentMethodType,

    /// The list of payment experiences enabled, if applicable for a payment method type
    pub payment_experience: Option<Vec<PaymentExperienceTypes>>,

    /// The list of card networks enabled, if applicable for a payment method type
    pub card_networks: Option<Vec<CardNetworkTypes>>,

    #[schema(deprecated)] // --------------------DEPRICATED-------------------------- //
    /// The list of banks enabled, if applicable for a payment method type
    pub bank_names: Option<Vec<BankCodeResponse>>,

    /// The Bank debit payment method information, if applicable for a payment method type.
    pub bank_debits: Option<BankDebitTypes>,

    /// The Bank transfer payment method information, if applicable for a payment method type.
    pub bank_transfers: Option<BankTransferTypes>,

    /// Required fields for the payment_method_type.
    pub required_fields: Option<HashMap<String, RequiredFieldInfo>>,

    /// surcharge details for this payment method type if exists
    pub surcharge_details: Option<SurchargeDetailsResponse>,

    /// auth service connector label for this payment method type, if exists
    pub pm_auth_connector: Option<String>,
}
```


## payment method types response


<details>
 <summary>Payment Request</summary>

```json 
{
  "payment_id": "pay_6W7NAlavGWBsNle4fjCm",
  "merchant_id": "merchant_1751973151",
  "status": "requires_payment_method",
  "amount": 6500,
  "net_amount": 6500,
  "amount_capturable": 0,
  "client_secret": "pay_6W7NAlavGWBsNle4fjCm_secret_cGp7blq0k5NBezW6gCmH",
  "created": "2025-07-08T11:49:13.894Z",
  "currency": "EUR",
  "customer_id": "hyperswitch_sdk_demo_id",
  "customer": {
    "id": "hyperswitch_sdk_demo_id",
    "email": "user@gmail.com"
  },
  "description": "Hello this is description",
  "setup_future_usage": "on_session",
  "capture_method": "automatic",
  "shipping": {
    "address": {
      "city": "Banglore",
      "country": "AT",
      "line1": "sdsdfsdf",
      "line2": "hsgdbhd",
      "line3": "alsksoe",
      "zip": "571201",
      "state": "California",
      "first_name": "John",
      "last_name": "Doe"
    },
    "phone": {
      "number": "123456789",
      "country_code": "+1"
    }
  },
  "billing": {
    "address": {
      "city": "San Fransico",
      "country": "AT",
      "line1": "1467",
      "line2": "Harrison Street",
      "line3": "Harrison Street",
      "zip": "94122",
      "state": "California",
      "first_name": "joseph",
      "last_name": "Doe"
    },
    "phone": {
      "number": "8056594427",
      "country_code": "+91"
    }
  },
  "order_details": [
    {
      "amount": 6500,
      "quantity": 1,
      "product_name": "Apple iphone 15"
    }
  ],
  "email": "user@gmail.com",
  "business_label": "default",
  "ephemeral_key": {
    "customer_id": "hyperswitch_sdk_demo_id",
    "created_at": 1751975353,
    "expires": 1751978953,
    "secret": "epk_78740ac9b3a7426e9ed57c14c801fb4f"
  },
  "metadata": {
    "udf1": "value1",
    "login_date": "2019-09-10T10:11:12Z",
    "new_customer": "true"
  },
  "connector_metadata": {
    "noon": {
      "order_category": "applepay"
    }
  },
  "profile_id": "pro_2UxGWjdVxvRMEw6zBI2V",
  "attempt_count": 1,
  "external_3ds_authentication_attempted": false,
  "expires_on": "2025-07-08T12:04:13.894Z",
  "updated": "2025-07-08T11:49:13.908Z",
  "force_3ds_challenge": false,
  "force_3ds_challenge_trigger": false
}

```

</details>



### GET http://localhost:8080/account/payment_methods?client_secret=pay_gvSgEeG6HZU6PnwbHhno_secret_gTL5Uke9uC8r3XGUs3Kx

```json
{
  "redirect_url": "https://google.com/success",
  "currency": "EUR",
  "payment_methods": [
    {
      "payment_method": "bank_redirect",
      "payment_method_types": [
        {
          "payment_method_type": "eps",
          "payment_experience": null,
          "card_networks": null,
          "bank_names": [
            {
              "bank_name": [
                "hypo_tirol_bank_ag",
                "brull_kallmus_bank_ag",
                "volkskreditbank_ag",
                "capital_bank_grawe_gruppe_ag",
                "btv_vier_lander_bank",
                "marchfelder_bank",
                "easybank_ag",
                "hypo_vorarlberg_bank_ag",
                "hypo_alpeadriabank_international_ag",
                "oberbank_ag",
                "hypo_noe_lb_fur_niederosterreich_u_wien",
                "volksbank_gruppe",
                "hypo_oberosterreich_salzburg_steiermark",
                "hypo_bank_burgenland_aktiengesellschaft",
                "dolomitenbank",
                "austrian_anadi_bank_ag",
                "raiffeisen_bankengruppe_osterreich",
                "sparda_bank_wien",
                "arzte_und_apotheker_bank",
                "bankhaus_schelhammer_und_schattera_ag",
                "bank_austria",
                "bawag_psk_ag",
                "schoellerbank_ag",
                "vr_bank_braunau",
                "erste_bank_und_sparkassen",
                "bankhaus_carl_spangler",
                "bks_bank_ag"
              ],
              "eligible_connectors": ["stripe"]
            }
          ],
          "bank_debits": null,
          "bank_transfers": null,
          "required_fields": {
            "billing.address.first_name": {
              "required_field": "payment_method_data.billing.address.first_name",
              "display_name": "billing_name",
              "field_type": "user_full_name",
              "value": "joseph"
            },
            "payment_method_data.bank_redirect.eps.bank_name": {
              "required_field": "payment_method_data.bank_redirect.eps.bank_name",
              "display_name": "bank_name",
              "field_type": {
                "user_bank_options": {
                  "options": [
                    "hypo_tirol_bank_ag",
                    "brull_kallmus_bank_ag",
                    "volkskreditbank_ag",
                    "capital_bank_grawe_gruppe_ag",
                    "btv_vier_lander_bank",
                    "marchfelder_bank",
                    "easybank_ag",
                    "hypo_vorarlberg_bank_ag",
                    "hypo_alpeadriabank_international_ag",
                    "oberbank_ag",
                    "hypo_noe_lb_fur_niederosterreich_u_wien",
                    "volksbank_gruppe",
                    "hypo_oberosterreich_salzburg_steiermark",
                    "hypo_bank_burgenland_aktiengesellschaft",
                    "dolomitenbank",
                    "austrian_anadi_bank_ag",
                    "raiffeisen_bankengruppe_osterreich",
                    "sparda_bank_wien",
                    "arzte_und_apotheker_bank",
                    "bankhaus_schelhammer_und_schattera_ag",
                    "bank_austria",
                    "bawag_psk_ag",
                    "schoellerbank_ag",
                    "vr_bank_braunau",
                    "erste_bank_und_sparkassen",
                    "bankhaus_carl_spangler",
                    "bks_bank_ag"
                  ]
                }
              },
              "value": null
            },
            "billing.address.last_name": {
              "required_field": "payment_method_data.billing.address.last_name",
              "display_name": "billing_name",
              "field_type": "user_full_name",
              "value": "Doe"
            }
          },
          "surcharge_details": null,
          "pm_auth_connector": null
        }
      ]
    }
  ],
  "mandate_payment": null,
  "merchant_name": "NewAge Retailer",
  "show_surcharge_breakup_screen": false,
  "payment_type": "normal",
  "request_external_three_ds_authentication": false,
  "collect_shipping_details_from_wallets": false,
  "collect_billing_details_from_wallets": false,
  "is_tax_calculation_enabled": false
}

```

Related Pr: https://github.com/juspay/hyperswitch/pull/8577

### Additional Changes

- [x] This PR modifies the API contract
- [x] This PR modifies the database schema
- [ ] This PR modifies application configuration/environment variables

<!--
Provide links to the files with corresponding changes.

Following are the paths where you can find config files:
1. `config`
2. `crates/router/src/configs`
3. `loadtest/config`
-->


## Motivation and Context
<!--
Why is this change required? What problem does it solve?
If it fixes an open issue, please link to the issue here.

If you don't have an issue, we'd recommend starting with one first so the PR
can focus on the implementation (unless it is an obvious bug or documentation fix
that will have little conversation).
-->


## How did you test it?
<!--
Did you write an integration/unit/API test to verify the code changes?
Or did you test this change manually (provide relevant screenshots)?
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## Checklist
<!-- Put an `x` in the boxes that apply -->

- [x] I formatted the code `cargo +nightly fmt --all`
- [x] I addressed lints thrown by `cargo clippy`
- [ ] I reviewed the submitted code
- [ ] I added unit tests for my changes where possible

<think>
PR Context:
- Title: fix(airwallex_bank_name): send ideal supported bank names inside the structs for sdk
- Merged: None
- Files changed: 9 files
- Commits: 10 commits

Implementation approach:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [x] Bugfix
- [ ] New feature
- [ ] Enhancement
- [ ] Refactoring
- [ ] Dependency updates
- [ ] Documentation
- [ ] CI/CD

## Description
<!-- Describe your changes in detail -->
Previously the bank names were hard coded but we needed to read form {config}.toml files to send the supported banks inside user_bank_options.
Reference PR: #8779 

<img width="1258" height="706" alt="Screenshot 2025-08-14 at 4 36 21 PM" sr
</think>

To implement this, you'll need to modify:


(No detailed commit information available)
{"issue_number": 8779, "pr_number": 8960, "commits_count": 0, "files_changed": 9, "response_length": 799, "file_count": 0, "needs_breakdown": false}