[ticket/13654] Moving reporting into controller

Moving report.php's content into different services and controllers to
better comply with the MVC model.

Also implementing:
 * Replacement for reasons_display()
 * Adding assign_meta_refresh_var() to \controller\helper
 * Adding separate routes for easy configuration
 * Updating unit tests to expect to correct results
 * Add BC tests

PHPBB3-13654

phpBB/config/default/routing/routing.yml

@@ -11,3 +11,6 @@
 phpbb_help_routing:
     resource: "help.yml"
     prefix: /help
+
+phpbb_report_routing:
+    resource: "report.yml"