Allow adding attributes to form element and disabling ajax validation

Features:

- Option to disable default ajax form validation by passing `"ajaxValidation" => false` parameter.
- Option to pass any form element attribute (`role="form"`, `ng-controller="ContactCtrl as ctrl"`) by 3rd parameter. _I left the class attribute in 2nd group for backward compatiblity_.
```php
<?php cockpit(
   "forms:form",
   "contact",
    ["ajaxValidation" => false],
    ["role" => "form", "ng-controller" => "ContactCtrl as ctrl"]
) ?>
```