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/users/confirmations_controller.rb

@@ -1,5 +1,4 @@
 class Users::ConfirmationsController < Devise::ConfirmationsController
-
   # new action, PATCH does not exist in the default Devise::ConfirmationsController
   # PATCH /resource/confirmation
   def update
@@ -55,5 +54,4 @@ class Users::ConfirmationsController < Devise::ConfirmationsController
     def set_official_position
       resource.add_official_position! (Setting["official_level_1_name"]), 1
     end
-
 end