Create class 'TwoFactorMechanismAlreadyEnabledException'

src/TwoFactorMechanismAlreadyEnabledException.php

@@ -0,0 +1,12 @@
+<?php
+
+/*
+ * PHP-Auth (https://github.com/delight-im/PHP-Auth)
+ * Copyright (c) delight.im (https://www.delight.im/)
+ * Licensed under the MIT License (https://opensource.org/licenses/MIT)
+ */
+
+namespace Delight\Auth;
+
+/** Exception that is thrown when a given mechanism for two-factor authentification has already been enabled */
+class TwoFactorMechanismAlreadyEnabledException extends AuthException {}