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

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

vendor/composer/autoload_files.php

@@ -0,0 +1,11 @@
+<?php
+
+// autoload_files.php @generated by Composer
+
+$vendorDir = dirname(dirname(__FILE__));
+$baseDir = dirname($vendorDir);
+
+return array(
+    '2cffec82183ee1cea088009cef9a6fc3' => $vendorDir . '/ezyang/htmlpurifier/library/HTMLPurifier.composer.php',
+    '757772e28a0943a9afe83def8db95bdf' => $vendorDir . '/mf2/mf2/Mf2/Parser.php',
+);