Give filters field more concise

[retsef]

I'm using ransack filters from 'administrate_ransack' for replicate the solidus_backend fields search functionality.

At this moment the choosing of witch filter fender for witch field is made with a switch case in the _filters.html.erb.
I think it need to be moved to a render_filter field approach to be concise with the administrate approach.

[retsef]

Some progress are made with filters_helper.rb but its better to render as a Field::Class like