Support StripeBank.createSource

[yringler]

In app/src/components/app.component.ts There's a property used, metadata, which is supposed to be a child property of BankAccountTokenOptions.
I opened up DefinitelyTyped/DefinitelyTyped/pull/50386, and a maintainer noted

metadata seems not to be a part of the tokenCreate method (or at least it's undocumented): https://stripe.com/docs/js/tokens_sources/create_token?type=bank_account

please be aware this is the types definition for the front-facing stripe.js library https://stripe.com/docs/js

What's the intent with this line of code? Should we remove the metadata property? Is it a mock response?

[AckerApple]

This was left because I didn't finish implementing bank account source and only did token.

I imagine I will be getting this right within 2 months maximum as I am not set to do ACH work until Q2 of this year

[AckerApple]

Steps to complete

• Review how the stripe-card component, in this repo, supports createSource, createToken, and createPaymentMethod
  • Replicate this logic for bank account
• Review and enhance the bank account demo area to support "createSource" as well as the existing "createToken"
• Documentation for updating a bank account including metadata