[ticket/11103] The start of an all-encompassing notifications system

This system will take input from various systems to store notifications
and send notifications to users all in one nice extendable system.

This system should act something like the notifications system on
other social networking sites (in that, there is a single location where
a user can see all of their notifications for various events).

PHPBB3-11103

phpBB/config/services.yml

@@ -89,6 +89,11 @@ services:
             - .%core.php_ext%
             - @cache.driver
 
+    notifications:
+        class: phpbb_notifications_service
+        arguments:
+            - @container
+
     processor.config:
         class: phpbb_di_processor_ext
         arguments: