[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/library/HTMLPurifier.path.php

@@ -0,0 +1,11 @@
+<?php
+
+/**
+ * @file
+ * Convenience stub file that adds HTML Purifier's library file to the path
+ * without any other side-effects.
+ */
+
+set_include_path(dirname(__FILE__) . PATH_SEPARATOR . get_include_path() );
+
+// vim: et sw=4 sts=4