graph/db: let ForEachNodeChannel take a context

graph/db/interfaces.go

@@ -83,7 +83,7 @@ type V1Store interface { //nolint:interfacebloat
 	// to the caller.
 	//
 	// Unknown policies are passed into the callback as nil values.
-	ForEachNodeChannel(nodePub route.Vertex,
+	ForEachNodeChannel(ctx context.Context, nodePub route.Vertex,
 		cb func(*models.ChannelEdgeInfo, *models.ChannelEdgePolicy,
 			*models.ChannelEdgePolicy) error) error