Replace __CLASS__ constant with self::class keyword master
Summary: `::class` is available since PHP 5.5. * https://www.php.net/manual/en/language.constants.magic.php * https://www.php.net/manual/en/language.oop5.basic.php#language.oop5.basic.class.class * https://wiki.php.net/rfc/class_name_scalars#considerations `::class` returns the fully qualified classname including namespace, however we do not use PHP namespaces except in imported external libraries untouched here. (Also, I ideally like to grep for 1 term when trying to find the same stuff.) Refs T15158 Test Plan: Browse random Phorge pages? Reviewers: O1 Blessed Committers, mainframe98 Reviewed By: O1 Blessed Committers, mainframe98 Subscribers: mainframe98, tobiaswiese, valerio.bozzolan, Matthew, Cigaryno Maniphest Tasks: T15158 Differential Revision: https://we.phorge.it/D26324