Tackle CollaborativeClose `todo!`

[luckysori]

rust-dlc/dlc-manager/src/sub_channel_manager.rs

Lines 3099 to 3104 in 724f598

	} else if let TxType::CollaborativeClose = channel_info.tx_type {
	todo!();
	// signed_channel.state = SignedChannelState::CollaborativelyClosed;
	// self.dlc_channel_manager.get_store()
	// .upsert_channel(Channel::Signed(signed_channel), None)?;
	}