refactor(payment_methods): add a new domain type for payment method data to be used in connector module

[Narayanbhat166]

Type of Change

• [x] Refactoring

Description

This PR adds a new domain type for payment_method_data to be used everywhere in the application.

Motivation and Context

We need to have separate types for api model and domain, currently we are using the api type in application as well.

How did you test it?

• Sanity test of payments.

Impact

• No impact on any flow or connector

Checklist

• [x] I formatted the code cargo +nightly fmt --all
• [x] I addressed lints thrown by cargo clippy