fix(payment_methos): prioritized apple_pay_combined deserialization over apple_pay

[ShankarSinghC]

Type of Change

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

Description

When the merchant_connector_account metadata contains both apple_pay and apple_pay_combined apple_pay data gets deserialized and it is used for the session call. But we expect apple_pay_combined to be used as it will contain the updated data. This pr contains the change in which the data is first deserialized into apple_pay_combined and then into apple_pay if it fails. By this we ensure apple_pay_combined is prioritized over apple_pay.

Additional Changes

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

Motivation and Context

How did you test it?

bluesnap session call

Test case :-
-> For the existing merchant update the new apple pay details and verify the apple pay payment.
-> Also manual apple pay flow for bluesnap and simplified apple pay flow for bluesnap needs to be tested.

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