[FEATURE]: Add `Payment Method - Delete` endpoint to payment methods session for V2

Required for Payment Methods Service
<think>
PR Context:
- Title: feat(router): Add payment_methods_session_delete_payment_method endpoint [V2]
- Merged: 2025-03-27T12:05:05Z
- Files changed: 11 files
- Commits: 12 commits

Implementation approach:

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

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

## Description
<!-- Describe your changes in detail -->
This endpoint allows deleting saved payment methods for a customer

### Additional Changes

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

To implement this, you'll need to modify:


**Detailed Implementation:**


**Commit 1:** feat(router): Add payment_methods_session_delete_payment_method endpoint [V2] (#7409)
Co-authored-by
Files to modify:


**crates/api_models/src/payment_methods.rs**
  Add:
    - struct: pub::PaymentMethodSessionDeleteSavedPaymentMethod

**crates/openapi/src/openapi_v2.rs**
  Modify existing code

**crates/openapi/src/routes/payment_method.rs**
  Add:
    - function: pub::payment_method_session_delete_saved_payment_method

**crates/router/src/core/payment_methods.rs**
  Add:
    - function: pub::payment_methods_session_delete_payment_method

**crates/router/src/routes/app.rs**
  Modify existing code

**crates/router/src/routes/lock_utils.rs**
  Modify existing code

**crates/router/src/routes/payment_methods.rs**
  Add:
    - function: pub::payment_method_session_delete_saved_payment_method

**crates/router_env/src/logger/types.rs**
  Modify existing code
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