graph/db: let ForEachNodeCached maybe fetch node addresses

Here we adjust the ForEachNodeCached graph DB method to pass in a node's
addresses into the provided call-back if requested. This will allow us
to improve the performance of node/channel iteration in the autopilot
subserver.

autopilot/graph.go

@@ -210,7 +210,8 @@ func (nc dbNodeCached) ForEachChannel(ctx context.Context,
 func (dc *databaseChannelGraphCached) ForEachNode(ctx context.Context,
 	cb func(context.Context, Node) error, reset func()) error {
 
-	return dc.db.ForEachNodeCached(ctx, func(n route.Vertex,
+	return dc.db.ForEachNodeCached(ctx, false, func(ctx context.Context,
+		n route.Vertex, _ []net.Addr,
 		channels map[uint64]*graphdb.DirectedChannel) error {
 
 		if len(channels) > 0 {
@@ -221,6 +222,7 @@ func (dc *databaseChannelGraphCached) ForEachNode(ctx context.Context,
 
 			return cb(ctx, node)
 		}
+
 		return nil
 	}, reset)
 }

autopilot/interface.go

@@ -235,7 +235,9 @@ type GraphSource interface {
 	// channel graph cache if one is available. It is less consistent than
 	// ForEachNode since any further calls are made across multiple
 	// transactions.
-	ForEachNodeCached(ctx context.Context, cb func(node route.Vertex,
-		chans map[uint64]*graphdb.DirectedChannel) error,
+	ForEachNodeCached(ctx context.Context, withAddrs bool,
+		cb func(ctx context.Context, node route.Vertex,
+			addrs []net.Addr,
+			chans map[uint64]*graphdb.DirectedChannel) error,
 		reset func()) error
 }