channeldb: added isPending flag and queries

In order to facilitate persistence during the funding process, added
the isPending flag to channels so that when the daemon restarts, we can
properly re-initialize the chain notifier and update the state of
channels that were going through the funding process.

lnwallet/reservation.go

@@ -204,6 +204,7 @@ func NewChannelReservation(capacity, fundingAmt btcutil.Amount, minFeeRate btcut
 		partialState: &channeldb.OpenChannel{
 			Capacity:     capacity,
 			IsInitiator:  initiator,
+			IsPending:    true,
 			ChanType:     chanType,
 			OurBalance:   ourBalance,
 			TheirBalance: theirBalance,