core: remove parent_id from the global event

Remove the parent_id from the global event. Remove the parent
and owner from the global object.

Use properties instead to mark parents and owners of objects.

Properties are easier to control for client exported objects and
usually a simple parent/child is not enough. For example, a client
exported node has the client as a parent but also the factory that
created the node.

src/pipewire/module.h

@@ -63,14 +63,16 @@ struct pw_module_events {
 
 	/** The module is destroyed */
 	void (*destroy) (void *data);
+
+	/** The module is registered. This is a good time to register
+	 * objectes created from the module. */
+	void (*registered) (void *data);
 };
 
 struct pw_module *
 pw_module_load(struct pw_core *core,
 	       const char *name,		/**< name of the module */
 	       const char *args			/**< arguments of the module */,
-	       struct pw_client *owner,		/**< optional owner */
-	       struct pw_global *parent,	/**< parent global */
 	       struct pw_properties *properties	/**< extra global properties */);
 
 /** Get the core of a module */