First successful DB connection to a phpBB installation

* added "before" actions middlewares management in Plugins config files. It is now possible to define Services names as middlewares for individual actions, as well as  middlewares triggered for the whole Plugins actions - which can be defined in the "general" section of the Plugin config file
* first 'auth.middleware.*" app common middlewares
* new 'html.escape' core Service
* new "secured Notifications" management (@see notifications-display.twig)
* new "TalkTalk\CorePlugins\Utils\ArrayUtils" class
* the usual CS fix