Notifications for channel closes/splices

[JssDWt]

Give lspd the option to send a webhook notification in order to wake up the peer for channel management, like closing a channel or splicing out liquidity.

The main question is how to shape this functionality.

• Will lspd automatically close/splice channels based on heuristics that can be configured?
• Will lspd expose an api for an administrator to close/splice channels?
• Will lspd only expose an api for an administrator to wake up a node in order to close/splice a channel?

The time sensitive nature of the mobile notification probably requires lspd to be in charge of handling the channel close/splice.

[kingonly]

I think exposing an API to close using notifications (instead of force closing rn) would be the first building block. Then automation/heuristics can be added, but need more feedback from LSPs.