Creates flexible content widget. Relies on ACF and Timber.
To override the template create corresponding templates in your themes views/flexible_content_widget dir
To override one specific entry create a template that matches
'flexible_content_widget/flexible_content_widget_' . $widget_id . '.twig'
where widget_id is eg "flex_widget-3" (look in the widget li's class list using inspector)
similarly for a specific content type you can use
'flexible_content_widget/content/' ~ item.template ~ '.twig'
where template is a field for the content type. See the included banner type.