add convenience method to check if a file is in the hidden folder

Signed-off-by: Robin Appelman <[email protected]>

lib/private/Files/Filesystem.php

@@ -901,4 +901,8 @@ public static function getETag($path) {
 	public static function getHiddenFolderName(): string {
 		return '.hidden_' . \OC_Util::getInstanceId();
 	}
+
+	public static function isPathHidden($path): string {
+		return strpos($path, self::getHiddenFolderName()) !== false;
+	}
 }