MDL-82706 filter: Bring back filter.php in the filter plugins

filter/codehighlighter/filter.php

@@ -0,0 +1,28 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * File only retained to prevent fatal errors in code that tries to require/include this.
+ *
+ * @todo MDL-82708 delete this file as part of Moodle 6.0 development.
+ * @deprecated This file is no longer required in Moodle 4.5+.
+ * @package filter_codehighlighter
+ * @copyright Meirza <meirza.arson@moodle.com>
+ * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+defined('MOODLE_INTERNAL') || die();
+
+debugging('This file is no longer required in Moodle 4.5+. Please do not include/require it.', DEBUG_DEVELOPER);