[CORE][COMPOSER] Move extlib packages with immediate composer correspondent to composer dependencies

This adds a composer.json for all dependencies that are available

vendor/ezyang/htmlpurifier/extras/HTMLPurifierExtras.autoload.php

@@ -0,0 +1,23 @@
+<?php
+
+/**
+ * @file
+ * Convenience file that registers autoload handler for HTML Purifier.
+ *
+ * @warning
+ *      This autoloader does not contain the compatibility code seen in
+ *      HTMLPurifier_Bootstrap; the user is expected to make any necessary
+ *      changes to use this library.
+ */
+
+if (function_exists('spl_autoload_register')) {
+    spl_autoload_register(array('HTMLPurifierExtras', 'autoload'));
+    if (function_exists('__autoload')) {
+        // Be polite and ensure that userland autoload gets retained
+        spl_autoload_register('__autoload');
+    }
+} elseif (!function_exists('__autoload')) {
+    require dirname(__FILE__) . '/HTMLPurifierExtras.autoload-legacy.php';
+}
+
+// vim: et sw=4 sts=4