refactor(connector): [Paypal] Add support for both BodyKey and SignatureKey

[swangi-kumari]

Type of Change

• Bugfix
• New feature
• Enhancement
• Refactoring
• Dependency updates
• Documentation
• CI/CD

Description

• Make PayPal support SignatureKey auth_type.
• Add extra fields in orders request.

Additional Changes

• This PR modifies the API contract
• This PR modifies the database schema
• This PR modifies application configuration/environment variables

Motivation and Context

To support PayPal onboarding flow.

How did you test it?

Postman.

Payment Connector - Create

Paypal now supports TemporaryAuth in the auth_type. You can find more details about this in this PR #2833.
Paypal also support SignatureKey in the auth_type.

curl --location 'http://localhost:8080/account/merchant_1700133263/connectors' \
--header 'Content-Type: application/json' \
--header 'Accept: application/json' \
--header 'api-key: test_admin' \
--data '{
  "connector_type": "fiz_operations",
  "connector_name": "paypal",
  "connector_account_details": {
    "auth_type": "SignatureKey",
    "api_key": "client_secret",
    "key1": "client_id",
    "api_secret": "partner_id"
  },
  "status": "active",
  "disabled": false
}'

If all the fields are passed correctly you will a normal mca response.

Checklist

• I formatted the code cargo +nightly fmt --all
• I addressed lints thrown by cargo clippy
• I reviewed the submitted code
• I added unit tests for my changes where possible
• I added a CHANGELOG entry if applicable