Refactor payment methods to have a unified Bank type

[Sarthak1799]

Feature Description

We need to have a unified bank struct in payment methods. This particular bank type should ideally be used across the application.

Possible Implementation

Will need to implement a unified type for bank related data that would be flow agnostic and to be used across payments, payment_methods, payouts, etc.
We'd start with a unified type for PaymentMethods + Payouts, later on move it to domain models (and possible api models) for Payments as well.