Add node for GoCardless

GoCardless is a major payment service for accepting direct debit payments.
A node supporting its most common operations like creating and managing mandates and initiating and tracking direct debits would be very helpful.

A cherry on top would be to to support status webhooks in a trigger node. :wink:

See API reference: https://developer.gocardless.com/api-reference/
It can be based on their own TypeScript-based Node-client: https://github.com/gocardless/gocardless-nodejs
Sandbox account can be created here: https://manage-sandbox.gocardless.com/signup

As always, happy to help! I can provide testing and feedback with our GC account.