Move all composer files inside the common directory

- 2022년 3월 개발팀 결정사항 적용
- 모듈 등 서드파티 자료 개발시 composer를 사용하면 상위 경로에 있는 코어의
  composer.json을 수정하고, 코어의 vendor 디렉토리를 건드리는 것이 기본값임
- 이를 방지하기 위해 코어의 composer.json과 vendor를 common 디렉토리 안으로
  이동하여, 모듈 경로에서 상위 폴더로 인식하지 않도록 함

common/vendor/ezyang/htmlpurifier/library/HTMLPurifier/AttrTransform.php

@@ -0,0 +1,60 @@
+<?php
+
+/**
+ * Processes an entire attribute array for corrections needing multiple values.
+ *
+ * Occasionally, a certain attribute will need to be removed and popped onto
+ * another value.  Instead of creating a complex return syntax for
+ * HTMLPurifier_AttrDef, we just pass the whole attribute array to a
+ * specialized object and have that do the special work.  That is the
+ * family of HTMLPurifier_AttrTransform.
+ *
+ * An attribute transformation can be assigned to run before or after
+ * HTMLPurifier_AttrDef validation.  See HTMLPurifier_HTMLDefinition for
+ * more details.
+ */
+
+abstract class HTMLPurifier_AttrTransform
+{
+
+    /**
+     * Abstract: makes changes to the attributes dependent on multiple values.
+     *
+     * @param array $attr Assoc array of attributes, usually from
+     *              HTMLPurifier_Token_Tag::$attr
+     * @param HTMLPurifier_Config $config Mandatory HTMLPurifier_Config object.
+     * @param HTMLPurifier_Context $context Mandatory HTMLPurifier_Context object
+     * @return array Processed attribute array.
+     */
+    abstract public function transform($attr, $config, $context);
+
+    /**
+     * Prepends CSS properties to the style attribute, creating the
+     * attribute if it doesn't exist.
+     * @param array &$attr Attribute array to process (passed by reference)
+     * @param string $css CSS to prepend
+     */
+    public function prependCSS(&$attr, $css)
+    {
+        $attr['style'] = isset($attr['style']) ? $attr['style'] : '';
+        $attr['style'] = $css . $attr['style'];
+    }
+
+    /**
+     * Retrieves and removes an attribute
+     * @param array &$attr Attribute array to process (passed by reference)
+     * @param mixed $key Key of attribute to confiscate
+     * @return mixed
+     */
+    public function confiscateAttr(&$attr, $key)
+    {
+        if (!isset($attr[$key])) {
+            return null;
+        }
+        $value = $attr[$key];
+        unset($attr[$key]);
+        return $value;
+    }
+}
+
+// vim: et sw=4 sts=4