Add notification plugin hook

shared/models/plugins/server/server-hook.model.ts

@@ -112,6 +112,9 @@ export const serverActionHookObject = {
   // Fired when the application has been loaded and is listening HTTP requests
   'action:application.listening': true,
 
+  // Fired when a new notification is created
+  'action:notifier.notification.created': true,
+
   // API actions hooks give access to the original express `req` and `res` parameters
 
   // Fired when a local video is updated