multi: rename AnnounceSignatures to AnnounceSignatures1

In preparation for adding a new message, AnnounceSignatures2 along with
an AnnounceSignatures interface, we rename the existing message to
AnnounceSignatures1.

graph/validation_barrier.go

@@ -153,7 +153,7 @@ func (v *ValidationBarrier) InitJobDependencies(job interface{}) {
 		return
 	case *channeldb.LightningNode:
 		return
-	case *lnwire.AnnounceSignatures:
+	case *lnwire.AnnounceSignatures1:
 		// TODO(roasbeef): need to wait on chan ann?
 		return
 	}
@@ -216,7 +216,7 @@ func (v *ValidationBarrier) WaitForDependants(job interface{}) error {
 
 	// Other types of jobs can be executed immediately, so we'll just
 	// return directly.
-	case *lnwire.AnnounceSignatures:
+	case *lnwire.AnnounceSignatures1:
 		// TODO(roasbeef): need to wait on chan ann?
 	case *models.ChannelEdgeInfo:
 	case *lnwire.ChannelAnnouncement:
@@ -301,7 +301,7 @@ func (v *ValidationBarrier) SignalDependants(job interface{}, allow bool) {
 		shortID := lnwire.NewShortChanIDFromInt(msg.ChannelID)
 		delete(v.chanEdgeDependencies, shortID)
 
-	case *lnwire.AnnounceSignatures:
+	case *lnwire.AnnounceSignatures1:
 		return
 	}
 }