style(payment): Update Coinbase payment modal.

[gtandersen]

Ref https://help.coinbase.com/en/migrating-to-the-onchain-payment-protocol and #1549.

[castaway]

lgtm

[castaway]

Oops, re-reviewed after Dave asked about non-coinbase .. This update removes the use of mainOptions from the html, are these no longer used / appropriate? if so we should removed all other references to them

[gtandersen]

Oops, re-reviewed after Dave asked about non-coinbase .. This update removes the use of mainOptions from the html, are these no longer used / appropriate? if so we should removed all other references to them

I will re-review this as well because we'll apparently need a way for customers to pay manually to Coinbase (without the Coinbase Commerce interface).

[gtandersen]

In order to satisfy customers' desire to without using Coinbase, the additional button below is intended to trigger initiateCryptoPayment() similar to the initiatePayment() in shopping-cart.component.ts and take the user to a cryptocurrency version of the payment receipt page with instructions on how to proceed: