feature request: If channel is in the active state, warn the user before force closing that cooperative close is preferred.

[beeforbacon]

When Force Close is selected as a channel close method in Thunderhub, I think there should be a bit of a warning if the channel is considered active, to remind the user that cooperative close is an option and that force closing is often more expensive and is a higher wait-time and should only be used as an absolute last resort to recover funds on chain.