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.

graph/db/graph_test.go

@@ -252,6 +252,24 @@ func TestNodeInsertionAndDeletion(t *testing.T) {
 	dbNode, err = graph.FetchLightningNode(ctx, testPub)
 	require.NoError(t, err)
 	require.Equal(t, expAddrs, dbNode.Addresses)
+
+	// Also check that the withAddr param of ForEachNodeCached correctly
+	// returns the addresses we expect for this node.
+	err = graph.ForEachNodeCached(
+		ctx, true, func(ctx context.Context, node route.Vertex,
+			addrs []net.Addr,
+			chans map[uint64]*DirectedChannel) error {
+
+			if node != dbNode.PubKeyBytes {
+				return nil
+			}
+
+			require.Equal(t, expAddrs, addrs)
+
+			return nil
+		}, func() {},
+	)
+	require.NoError(t, err)
 }
 
 // TestPartialNode checks that we can add and retrieve a LightningNode where
@@ -1359,7 +1377,8 @@ func TestGraphTraversal(t *testing.T) {
 	// set of channels (to force the fall back), we should find all the
 	// channel as well as the nodes included.
 	graph.graphCache = nil
-	err := graph.ForEachNodeCached(ctx, func(node route.Vertex,
+	err := graph.ForEachNodeCached(ctx, false, func(_ context.Context,
+		node route.Vertex, _ []net.Addr,
 		chans map[uint64]*DirectedChannel) error {
 
 		if _, ok := nodeIndex[node]; !ok {