multi: Set upfront shutdown from open and accept chanel messages

This commit gets upfront shutdown scripts from openchannel and
acceptchannel wire messages sent from our peer and sets upfront
shutdown scripts in our open and accept channel messages when
the remote peer supports option upfront shutdown and we have
the feature enabled.

lnwallet/wallet.go

@@ -1217,6 +1217,13 @@ func (l *LightningWallet) handleFundingCounterPartySigs(msg *addCounterPartySigs
 	// rebroadcast on startup in case we fail.
 	res.partialState.FundingTxn = fundingTx
 
+	// Set optional upfront shutdown scripts on the channel state so that they
+	// are persisted. These values may be nil.
+	res.partialState.LocalShutdownScript =
+		res.ourContribution.UpfrontShutdown
+	res.partialState.RemoteShutdownScript =
+		res.theirContribution.UpfrontShutdown
+
 	// Add the complete funding transaction to the DB, in its open bucket
 	// which will be used for the lifetime of this channel.
 	nodeAddr := res.nodeAddr
@@ -1376,6 +1383,13 @@ func (l *LightningWallet) handleSingleFunderSigs(req *addSingleFunderSigsMsg) {
 		return
 	}
 
+	// Set optional upfront shutdown scripts on the channel state so that they
+	// are persisted. These values may be nil.
+	chanState.LocalShutdownScript =
+		pendingReservation.ourContribution.UpfrontShutdown
+	chanState.RemoteShutdownScript =
+		pendingReservation.theirContribution.UpfrontShutdown
+
 	// Add the complete funding transaction to the DB, in it's open bucket
 	// which will be used for the lifetime of this channel.
 	chanState.LocalChanCfg = pendingReservation.ourContribution.toChanConfig()