Added missing beforeCopy option to FileHelper::copyDirectory

It was mentioned in AssetManager::publish phpdoc.

framework/yii/helpers/BaseFileHelper.php

@@ -155,6 +155,11 @@ class BaseFileHelper
 	 *   and '.svn/' matches directory paths ending with '.svn'. Note, the '/' characters in a pattern matches
 	 *   both '/' and '\' in the paths.
 	 * - recursive: boolean, whether the files under the subdirectories should also be copied. Defaults to true.
+	 * - beforeCopy: callback, a PHP callback that is called before copying each sub-directory or file.
+	 *   This option is used only when publishing a directory. If the callback returns false, the copy
+	 *   operation for the sub-directory or file will be cancelled.
+	 *   The signature of the callback should be: `function ($from, $to)`, where `$from` is the sub-directory or
+	 *   file to be copied from, while `$to` is the copy target.
 	 * - afterCopy: callback, a PHP callback that is called after each sub-directory or file is successfully copied.
 	 *   The signature of the callback should be: `function ($from, $to)`, where `$from` is the sub-directory or
 	 *   file copied from, while `$to` is the copy target.
@@ -173,6 +178,9 @@ class BaseFileHelper
 			$from = $src . DIRECTORY_SEPARATOR . $file;
 			$to = $dst . DIRECTORY_SEPARATOR . $file;
 			if (static::filterPath($from, $options)) {
+				if (isset($options['beforeCopy'])) {
+					call_user_func($options['beforeCopy'], $from, $to);
+				}
 				if (is_file($from)) {
 					copy($from, $to);
 					if (isset($options['fileMode'])) {