notificaiton: improve NotificationHandlerInterface + mark notification

as unread if a comment is appended

src/Bundle/ChillMainBundle/Notification/NotificationHandlerInterface.php

@@ -18,7 +18,7 @@ interface NotificationHandlerInterface
     /**
      * Return the template path (twig file).
      */
-    public function getTemplate(array $options = []): string;
+    public function getTemplate(Notification $notification, array $options = []): string;
 
     /**
      * Return an array which will be passed as data for the template.