feat: replace after_form/before_form view blocks with form.before/form.after
feat: replace after_form/before_form view blocks with form.before/form.after

This standardizes view blocks names in use by form pages.

- introduces `form.before` viewblock
- introduces `form.after` viewblock
- removes `before_form` viewblock
- removes `after_form` viewblock

FriendsOfCake/crud-view,FriendsOfCake/crud-view,FriendsOfCake/crud-view