Add and apply Layout/EmptyLinesAfterModuleInclusion rule

This rule was added in rubocop 1.79. We were inconsistent about it, so
we're adding it to get more consistency.

spec/controllers/concerns/has_filters_spec.rb

@@ -3,6 +3,7 @@ require "rails_helper"
 describe HasFilters do
   controller(ActionController::Base) do
     include HasFilters
+
     has_filters ["all", "pending", "reviewed"], only: :index
 
     def index

spec/controllers/concerns/has_orders_spec.rb

@@ -3,6 +3,7 @@ require "rails_helper"
 describe HasOrders do
   controller(ActionController::Base) do
     include HasOrders
+
     has_orders ["created_at", "votes_count", "flags_count", "relevance"], only: :index
     has_orders ->(c) { ["votes_count", "flags_count"] }, only: :new