MDL-78613 TinyMCE: Add source code formatting and styling

Add code formatting (indenting) as well as code style (tag color)
via a TinyMC plugin. To make it easier to make code edits when
viewing the editor content in source code view.

lib/editor/tiny/plugins/html/classes/plugininfo.php

@@ -0,0 +1,37 @@
+<?php
+// This file is part of Moodle - https://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 <https://www.gnu.org/licenses/>.
+
+/**
+ * Tiny TinyMCE HTML formatter plugin for Moodle.
+ *
+ * @package     tiny_html
+ * @copyright   2023 Matt Porritt <[email protected]>
+ * @license     https://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace tiny_html;
+
+use editor_tiny\plugin;
+
+/**
+ * Tiny TinyMCE HTML formatter plugin for Moodle.
+ *
+ * @package     tiny_html
+ * @copyright   2023 Matt Porritt <[email protected]>
+ * @license     https://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class plugininfo extends plugin {
+}