Onchain payments

[darioAnongba]

Implement onchain payments:

• Fill account by receiving a payment onchain:
  • CLN: Receive on node, get event via websocket that amount has been received, link with user_id by invoice address or label
  • Breez: Receive via Swap. Get event with listener and link with user_id
  • CLN gRPC: ?
• Send onchain
  • CLN: Not implemented at the moment as the user controls the node so there is no need for now to allow this as it is complicated unless we reimplement the swapping method of Breez.
  • Breez: Use swaps