lnwallet: thread through tx conf details in ChannelReservation.DispatchChan()

This commit slightly modifies the channel reservation workflow to
expose the new information conerning the exact confirmation location of
the channel provided by the ChainNotifier. The DispatchChan() method of
the ChannelReservation now also returns the blockHeight and txIndex
where the transaction was ultimately confirmed. This information will
be needed by the fundingManager so it can properly generate the
authenticated channel announcement proofs.

lnwallet/reservation.go

@@ -121,10 +121,11 @@ type ChannelReservation struct {
 	// channel should be considered open.
 	numConfsToOpen uint16
 
-	// A channel which will be sent on once the channel is considered
-	// 'open'. A channel is open once the funding transaction has reached
-	// a sufficient number of confirmations.
-	chanOpen chan *LightningChannel
+	// chanOpen houses a struct containing the channel and additional
+	// confirmation details will be sent on once the channel is considered
+	// 'open'. A channel is open once the funding transaction has reached a
+	// sufficient number of confirmations.
+	chanOpen chan *openChanDetails
 
 	wallet *LightningWallet
 }
@@ -208,7 +209,7 @@ func NewChannelReservation(capacity, fundingAmt btcutil.Amount, minFeeRate btcut
 		},
 		numConfsToOpen: numConfs,
 		reservationID:  id,
-		chanOpen:       make(chan *LightningChannel, 1),
+		chanOpen:       make(chan *openChanDetails, 1),
 		wallet:         wallet,
 	}
 }
@@ -437,8 +438,12 @@ func (r *ChannelReservation) Cancel() error {
 //
 // NOTE: If this method is called before .CompleteReservation(), it will block
 // indefinitely.
-func (r *ChannelReservation) DispatchChan() <-chan *LightningChannel {
-	return r.chanOpen
+func (r *ChannelReservation) DispatchChan() (*LightningChannel, uint32, uint32) {
+	// TODO(roasbeef): goroutine sending in wallet should be lifted up into
+	// the fundingMgr
+	openDetails := <-r.chanOpen
+
+	return openDetails.channel, openDetails.blockHeight, openDetails.txIndex
 }
 
 // FinalizeReservation completes the pending reservation, returning an active
@@ -455,5 +460,5 @@ func (r *ChannelReservation) FinalizeReservation() (*LightningChannel, error) {
 		err:              errChan,
 	}
 
-	return <-r.chanOpen, <-errChan
+	return (<-r.chanOpen).channel, <-errChan
 }