Issue #3279298 by mferanda: Support for USWDS file input field

{#

/**

 * @file

 * Default theme implementation for an 'input' #type form element.

 *

 * Available variables:

 * - attributes: A list of HTML attributes for the input element.

 * - children: Optional additional rendered elements.

 * - icon: An icon.

 * - input_group: Flag to display as an input group.

 * - icon_position: Where an icon should be displayed.

 * - prefix: Markup to display before the input element.

 * - suffix: Markup to display after the input element.

 * - type: The type of input.

 *

 * @ingroup templates

 *

 * @see \Drupal\bootstrap\Plugin\Preprocess\Input

 * @see template_preprocess_input()

 */

#}

{% spaceless %}

  {% if input_group %}

    <div class="input-group usa-form-group">

  {% endif %}

  {% if prefix %}

    {{ prefix }}

  {% endif %}

  {% block input %}

    <input{{ attributes.addClass('usa-file-input') }} />

  {% endblock %}

  {% if suffix %}

    {{ suffix }}

  {% endif %}

  {% if input_group %}

    </div>

  {% endif %}

  {{ children }}

{% endspaceless %}