Adyen Native Integration

[mnida]

Is your feature request related to a problem? Please describe.
Customers want to pay through paypal/braintree not just through Stripe

Describe the solution you'd like
Add braintree to our payment processor integrations. Similar to Stripe's integration.

This needs to be able to

issue payments
issue invoices
receive webhooks on payment received
import customers from Braintree and merge into lotus
create customer in braintree
This should allow the next PSP integration to be much easier since these steps should be fairly reproducible and are already defined for Stripe in an extensible way in the backend.

The last bit of this will be creating a card in the frontend and connecting either via oauth or more easily (MVP) through a secret api key.

Additional Information

Starting with Oauth for this is great and then building the functions one by one after that. Can use Nango for Oauth most likely.
Take a look at how we did the Stripe and Braintree Integrations and start with those.