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/moderation/base_controller.rb

@@ -11,5 +11,4 @@ class Moderation::BaseController < ApplicationController
     def verify_moderator
       raise CanCan::AccessDenied unless current_user&.moderator? || current_user&.administrator?
     end
-
 end

app/controllers/moderation/budgets/investments_controller.rb

@@ -20,5 +20,4 @@ class Moderation::Budgets::InvestmentsController < Moderation::BaseController
     def resource_model
       Budget::Investment
     end
-
 end

app/controllers/moderation/dashboard_controller.rb

@@ -1,6 +1,4 @@
 class Moderation::DashboardController < Moderation::BaseController
-
   def index
   end
-
 end

app/controllers/moderation/debates_controller.rb

@@ -16,5 +16,4 @@ class Moderation::DebatesController < Moderation::BaseController
     def resource_model
       Debate
     end
-
 end

app/controllers/moderation/users_controller.rb

@@ -1,5 +1,4 @@
 class Moderation::UsersController < Moderation::BaseController
-
   before_action :load_users, only: :index
 
   load_and_authorize_resource
@@ -29,5 +28,4 @@ class Moderation::UsersController < Moderation::BaseController
       @user.block
       Activity.log(current_user, :block, @user)
     end
-
 end