Add and apply rubocop rules for empty lines

We were very inconsistent regarding these rules.

Personally I prefer no empty lines around blocks, clases, etc... as
recommended by the Ruby style guide [1], and they're the default values
in rubocop, so those are the settings I'm applying.

The exception is the `private` access modifier, since we were leaving
empty lines around it most of the time. That's the default rubocop rule
as well. Personally I don't have a strong preference about this one.


[1] https://rubystyle.guide/#empty-lines-around-bodies

app/controllers/organizations/registrations_controller.rb

@@ -1,5 +1,4 @@
 class Organizations::RegistrationsController < Devise::RegistrationsController
-
   invisible_captcha only: [:create], honeypot: :address, scope: :user
 
   def new
@@ -35,5 +34,4 @@ class Organizations::RegistrationsController < Devise::RegistrationsController
       params.require(:user).permit(:email, :password, :phone_number, :password_confirmation, :terms_of_service,
                                    organization_attributes: [:name, :responsible_name])
     end
-
 end