Fix fatal when scaffolding a FieldWidget. (#4239)

Author: Artusamak

templates/module/src/Plugin/Field/FieldWidget/fieldwidget.php.twig

@@ -12,6 +12,8 @@ namespace Drupal\{{ module }}\Plugin\Field\FieldWidget;
 use Drupal\Core\Field\FieldItemListInterface;
 use Drupal\Core\Field\WidgetBase;
 use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Field\Annotation\FieldWidget;
+use Drupal\Core\Annotation\Translation;
 {% endblock %}
 
 {% block class_declaration %}