use a respond_with helper in controllers

[madhums]

Improve readability of controller methods by using simpler and shorter respond_with methods

Inspired by

• https://allaboutcoding.ghinda.com/an-endless-method-use-case
• https://github.com/heartcombo/devise/blob/main/app/controllers/devise/sessions_controller.rb
• https://github.com/heartcombo/responders