Don't discard create _channel if a peer goes away

[TheBlueMatt]

Or if they're not connected. We should just retry for a timer tick and then generate a ChannelFailed. Docs should note that users can always refuse to fund or force close if they don't want a channel, but the peer getting disconnected at an exactly inopportune moment seems not worth failing for.

[jbesraa]

happy to try and do this one.
not sure though where exactly to start.. is this something should be in rust-lightning/lightning/src/ln/channelmanager.rs ?

[TheBlueMatt]

I'm not sure this is a great first issue. Probably better to look for the good first issue tag :)

[TheBlueMatt]

Slipping to 0.1, this is a bit of work and not super critical.