Implement Alby Wallet API as payments processor

[cameri]

Is your feature request related to a problem? Please describe.
Alby Wallet API can be used as a payments processor: https://guides.getalby.com/alby-wallet-api/reference/getting-started

Describe the solution you'd like

1. Allow relay operators to choose alby as payments processor

[Justxd22]

any plans to support this ? if yes please assign! Diving into their docs now

[cameri]

Done!

[Justxd22]

merged #539