feat: move events to transactions service

[rolznz]

Closes #350
Fixes #515
Fixes #516
Fixes #322
Fixes #422

This PR enable notifications for self payments, and keysend self-payments.

ln clients that do not support notifications will not receive events currently because the app connections won't have the permission.

Notable changes

• standard events are now "payment_sent", "payment_received", "payment_failed" (payment_succeeded is now payment_sent)
• lnclient events are prefixed with "lnclient_" and only consumed by the transactions service
• internal keysend payments are now possible
• NIP-47 notifications are fired for internal payments
• NIP-47 notifications are fired for lnclients that do not support notifications (using fallback method of checking unsettled transactions) - but they are currently filtered out due to the apps not having permission to fire them.
• No longer necessary to order event consumers as they are unlinked (NIP-47 notifier now uses transaction service events)
• New DB column on transactions: failure_reason

TODOs

• only have one payment_sent and one payment_failed event, but triggered from transaction service. - the lnclient ones should be renamed to be clearly different.
• NIP-47 notifier should consume these events.
• internal keysends
• reduce duplication in self payment interception code
• Fix offset paging bug
• Fix payment permission denied event not firing
• Fix error: payment already marked as sent
• Unit Tests:
  • paging
  • Send payment should check for existing successful payment before sending, otherwise wrong error code is possible (e.g. budget exceeded)
  • Send nwc permission denied event on payment
  • marking transaction as settled cannot be done twice (to avoid duplicate notification)
    • sent
    • received
  • marking payment as failed cannot be done twice (to avoid duplicate notification)
  • transaction service - firing events
    • payment sent
    • payment received
  • keysend self payments
  • notifications
    • now work for e.g. cashu client (using check unsettled transaction code)
    • internal keysends
• Manual tests
  • internal keysend payment with boostagram
  • events correctly fired
    • payment_sent
    • payment_received
    • payment_failed
    • alby oauth client - review data
  • nip-47 notifications
    • for other wallet types e.g. cashu/phoenix - ❌ does not work unless we always mark that we support notifications - which might cause issues with apps because then they would not poll
    • keysend self-payment
    • wallet self-payment