[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/report.yml

@@ -0,0 +1,17 @@
+phpbb_report_pm_controller:
+    path:             /pm/{id}/report
+    methods:          [GET, POST]
+    defaults:
+        _controller:  phpbb.report.controller:handle
+        mode:         "pm"
+    requirements:
+        id:           \d+
+
+phpbb_report_post_controller:
+    path:             /post/{id}/report
+    methods:          [GET, POST]
+    defaults:
+        _controller:  phpbb.report.controller:handle
+        mode:         "post"
+    requirements:
+        id:           \d+