Adding channel with external node/LSP

[JeanlChristophe]

A user should have the possibility to connet channels from others LSP or nodes.

Example or the process:

• Get start with Spending balance

• Select "External node"

here external node is a bit mislanding: users could think they can use a remote node with Bitkit. maybe here we can say External channel?

• LNURL Channel or Connected Manually - LNURL chanel - Manual https://github.com/synonymdev/bitkit/issues/1972

[Jasonvdb]

PR with instructions on how to implement in LDK are here https://github.com/synonymdev/react-native-ldk/pull/268