jack: improve activate/deactivate

Add the nodes from the RT thread.
Handle non-realtime clients, we don't need to signal them
do some sort of latency callbacks
Don't do callbacks for clients without a handler.

src/modules/module-jack/server.h

@@ -27,6 +27,7 @@ struct jack_client {
 	struct spa_hook node_listener;
 	struct spa_list client_link;
 	bool activated;
+	bool realtime;
 };
 
 struct jack_server {