Implement form_ methods like in Symfony

[freezy-sk]

Current usage of ActiveForm is really complicated.
It requires combination of {{ use() }}, {% set form %} and |raw.

{{ use('yii/widgets/ActiveForm') }}
{% set form = active_form_begin({
    'id' : 'login-form',
    'options' : {'class' : 'form-horizontal'},
}) %}
    {{ form.field(model, 'username') | raw }}
    {{ form.field(model, 'password').passwordInput() | raw }}

    <div class="form-group">
        <input type="submit" value="Login" class="btn btn-primary" />
    </div>
{{ active_form_end() }}

It can be simplified like Symfony's form_ functions
https://symfony.com/doc/current/reference/forms/twig_reference.html