`Channel::is_pre_funded_state` is used incorrectly in `Channel::is_funding_broadcast`

[TheBlueMatt]

Channel::is_pre_funded_state got updated to return true when there's an interactive signing session available, but that looks wrong in the context of is_funding_broadcast (the funding is definitely not broadcasted!) but also generally seems wrong (shouldn't we check the state of the interactive signing session before we assume its far enough along that we should generate a closing ChannelMonitorUpdate, as its used in the force-closure pipeline, or before deciding to keep the channel around on disconnect, as in remove_uncommitted_htlcs_and_mark_paused).

[wpaulino]

Seems like just the uses in is_funding_broadcast and force_shutdown need to be updated? The interactive-tx protocol allows us to resume channel negotiation on restarts, so we don't need to forget the pending channel on disconnects.

[TheBlueMatt]

Hmm, is_funding_broadcast is also used to filter Channels before writing them to disk, so that would break resume, though is_funding_broadcast becomes a misnomer and we should check how else its used.

[TheBlueMatt]

Also is_pre_funded_state is a misnomer and should probably be renamed too :/