BECS: Process Payment with a Saved Payment Method and account PM management

[cesarcosta99]

This task involves implementing support for processing payments using a previously saved BECS payment method. Additionally, it includes determining whether BECS supports saving for future use and ensuring full payment method management.

• Determine if BECS supports saving for future use.

If supported:

• Ensure BECS can be saved at checkout.
• Ensure a simple product can be successfully purchased using a saved BECS payment method.
• Implement management features in My Account, including:
  • Adding a new BECS payment method.
  • Deleting an existing BECS payment method.
  • Setting a saved BECS payment method as the default.
• Add unit tests to cover saved BECS functionalities.