Revert callable type of Form::$onSuccess to accept mixed (#223)

* Add missing import

* Fix callable type in Form::$onSuccess

* Revert callable type of Form::$onSuccess to accept mixed (closes #224)

Author: jiripudil

src/Forms/Form.php

@@ -81,7 +81,7 @@ class Form extends Container implements Nette\Utils\IHtmlString
 	/** @internal protection token ID */
 	public const PROTECTOR_ID = '_token_';
 
-	/** @var callable[]&((callable(Form, array): void)|(callable(Form, ArrayHash): void))[]; Occurs when the form is submitted and successfully validated */
+	/** @var callable[]&((callable(Form, mixed): void))[]; Occurs when the form is submitted and successfully validated */
 	public $onSuccess;
 
 	/** @var callable[]&(callable(Form): void)[]; Occurs when the form is submitted and is not valid */