Make the report controller and helper classes accept the more generic
phpbb/config/config base class in their constructors, instead of the
specific database implementation phpbb/config/db.
PHPBB3-14729
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
