Apply Layout/LineLength rubocop rule

Note we're excluding a few files:

* Configuration files that weren't generated by us
* Migration files that weren't generated by us
* The Gemfile, since it includes an important comment that must be on
  the same line as the gem declaration
* The Budget::Stats class, since the heading statistics are a mess and
  having shorter lines would require a lot of refactoring

spec/components/admin/site_customization/pages/index_component_spec.rb

@@ -1,6 +1,7 @@
 require "rails_helper"
 
-describe Admin::SiteCustomization::Pages::IndexComponent, controller: Admin::SiteCustomization::PagesController do
+describe Admin::SiteCustomization::Pages::IndexComponent,
+         controller: Admin::SiteCustomization::PagesController do
   before { SiteCustomization::Page.delete_all }
 
   it "shows date in created_at and updated_at fields" do