Allow saving a position when create a widget card

We are ensuring that only position field is rendered only on
non-header cards.

Note that we have 3 sections that use widget cards:
- Homepage (cards and header cards)
- Custompages (only have cards)
- Sdg Homepage (cards and header cards)

app/controllers/concerns/admin/widget/cards_actions.rb

@@ -45,7 +45,7 @@ module Admin::Widget::CardsActions
 
     def allowed_params
       [
-        :link_url, :button_text, :button_url, :alignment, :header, :columns,
+        :link_url, :button_text, :button_url, :alignment, :header, :columns, :order,
         translation_params(Widget::Card),
         image_attributes: image_attributes
       ]