localchans: recreate missing edge if not found

If a node contains a channel, but doesn't have a corresponding edge in
the graph database, updating the channel policy would fail. In this
commit the edge is recreated if the channel exists. This ensures a node
can recover from a missing edge in the graph database by calling
updatechanpolicy.

rpcserver.go

@@ -7762,7 +7762,7 @@ func (r *rpcServer) UpdateChannelPolicy(ctx context.Context,
 	// With the scope resolved, we'll now send this to the local channel
 	// manager so it can propagate the new policy for our target channel(s).
 	failedUpdates, err := r.server.localChanMgr.UpdatePolicy(chanPolicy,
-		targetChans...)
+		req.CreateMissingEdge, targetChans...)
 	if err != nil {
 		return nil, err
 	}