Payment Intent and MCA changes for split payments

- Add split_txns_enabled field in PaymentIntent
- Add split_enabled field to MCA payment_method
- Code changes to modify split_enabled for a payment method when creating or updating an MCA (similar to recurring_enabled)
- PML changes to filter payment methods based on split_enabled in MCA and split_txns_enabled in Intent
<think>
PR Context:
- Title: feat(router): Payment Intent and MCA changes for split payments
- Merged: 2025-09-01T13:47:28Z
- Files changed: 20 files
- Commits: 5 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 -->
- Add split_txns_enabled field to business_profile DB, create+update API calls
- Add split_txns_enabled field in PaymentIntent
- PML changes to filter payment methods based on split_enabled in MCA and split_txns_enabled in Intent

### Addi
</think>

To implement this, you'll need to modify:


**Detailed Implementation:**


**Commit 1:** feat(router): Payment Intent and MCA changes for split payments (#9049)
Files to modify:


**crates/api_models/src/admin.rs**
  Modify existing code

**crates/api_models/src/payments.rs**
  Modify existing code

**crates/common_enums/src/enums.rs**
  Add:
    - enum: pub::SplitTxnsEnabled

**crates/diesel_models/src/business_profile.rs**
  Modify existing code

**crates/diesel_models/src/payment_intent.rs**
  Modify existing code

**crates/diesel_models/src/schema_v2.rs**
  Modify existing code

**crates/hyperswitch_domain_models/src/business_profile.rs**
  Modify existing code

**crates/hyperswitch_domain_models/src/payments.rs**
  Modify existing code

**crates/hyperswitch_domain_models/src/payments/payment_intent.rs**
  Modify existing code

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

**crates/router/src/core/admin.rs**
  Modify existing code

**crates/router/src/core/payments/transformers.rs**
  Modify existing code

**crates/router/src/services/kafka/payment_intent.rs**
  Modify existing code

**crates/router/src/services/kafka/payment_intent_event.rs**
  Modify existing code

**crates/router/src/types/api/admin.rs**
  Modify existing code
{"issue_number": 9047, "pr_number": 9049, "commits_count": 1, "files_changed": 20, "response_length": 1976, "file_count": 17, "needs_breakdown": true}