Issue: Add onboarding flow for VSAAS

- Support for endpoint to create a platform 
- Create platform org and platform merchant account
- Support to create connected merchant account inside platform org
- Modify existing list responses for org and merchant, to distinguish platform from standard.

Resolution: <think>
PR Context:
- Title: feat(vsaas): integrate onboarding flow for vertical saas
- Merged: 2025-05-12T15:02:09Z
- Files changed: 22 files
- Commits: 11 commits

Implementation approach:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [ ] Bugfix
- [x] New feature
- [x] Enhancement
- [x] Refactoring
- [ ] Dependency updates
- [ ] Documentation
- [ ] CI/CD

## Description
The PR supports onboarding for new VSAAS merchants. 
- Creating Platform Org
- Creation of Platform, and connected merchant accounts
- Change List response of merchant and organization list.

### Additional Changes

- [ ] This PR modifies the API contract
- [x] This PR modifie
</think>

To implement this, you'll need to modify:


**Detailed Implementation:**


**Commit 1:** feat(vsaas): integrate onboarding flow for vertical saas (#7884)
Files to modify:


**crates/api_models/src/events/user.rs**
  Modify existing code

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

**crates/api_models/src/user.rs**
  Add:
    - struct: pub::PlatformAccountCreateRequest
    - struct: pub::PlatformAccountCreateResponse

**crates/common_enums/src/enums.rs**
  Modify existing code

**crates/common_enums/src/enums/accounts.rs**
  Add:
    - enum: pub::MerchantAccountType
    - enum: pub::OrganizationType

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

**crates/diesel_models/src/organization.rs**
  Add:
    - function: pub::get_organization_type
    - function: pub::get_organization_type

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

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

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

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

**crates/router/src/core/user.rs**
  Add:
    - function: pub::create_platform_account

**crates/router/src/db/organization.rs**
  Modify existing code

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

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

**crates/router/src/routes/user.rs**
  Add:
    - function: pub::create_platform

**crates/router/src/types/domain/user.rs**
  Add:
    - function: private::from
    - function: private::try_from
    - impl: impl From<user_api::PlatformAccountCreateRequest> for NewUserOrganization
    - impl: impl TryFrom<user_api::PlatformAccountCreateRequest> for NewUserMerchant

**crates/router/src/types/transformers.rs**
  Modify existing code

**crates/router/src/utils/user.rs**
  Add:
    - function: pub::generate_env_specific_merchant_id

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