Do not check `ActiveStorage::Engine` when updating to 5.2

When upgrading from 5.1 to 5.2, if the application did not require
`rails/all`, `ActiveStorage` not be defined.
In that case, Acttive Storage content is not generated regardless of whether
the user wants to use or not.

As for the new component, I think it is preferable to check whether to
use it for the user, but since it is not yet able to deal with it, I
think that it is good to forcibly generate the content.

railties/lib/rails/app_updater.rb

@@ -22,7 +22,7 @@ def app_generator
         def generator_options
           options = { api: !!Rails.application.config.api_only, update: true }
           options[:skip_active_record]  = !defined?(ActiveRecord::Railtie)
-          options[:skip_active_storage] = !defined?(ActiveStorage::Engine) || !defined?(ActiveRecord::Railtie)
+          options[:skip_active_storage] = !defined?(ActiveRecord::Railtie)
           options[:skip_action_mailer]  = !defined?(ActionMailer::Railtie)
           options[:skip_action_cable]   = !defined?(ActionCable::Engine)
           options[:skip_sprockets]      = !defined?(Sprockets::Railtie)

railties/test/generators/app_generator_test.rb

 # frozen_string_literal: true
 
 require "generators/generators_test_helper"
-require "rails/generators/rails/app/app_generator"
 require "generators/shared_generator_tests"
+require "rails/generators/rails/app/app_generator"
+require "rails/app_updater"
 
 DEFAULT_APP_FILES = %w(
   .gitignore
@@ -315,31 +316,29 @@ def test_active_storage_mini_magick_gem
     assert_file "Gemfile", /^# gem 'mini_magick'/
   end
 
-  def test_app_update_does_not_generate_active_storage_contents_when_skip_active_storage_is_given
+  def test_app_update_generate_active_storage_contents_when_active_storage_does_not_defined
     app_root = File.join(destination_root, "myapp")
     run_generator [app_root, "--skip-active-storage"]
 
-    FileUtils.cd(app_root) do
-      quietly { system("bin/rails app:update") }
-    end
+    gen = Rails::AppUpdater.app_generator
+    gen.shell = @shell
+    gen.destination_root = app_root
+
+    quietly { gen.update_config_files }
 
     assert_file "#{app_root}/config/environments/development.rb" do |content|
-      assert_no_match(/config\.active_storage/, content)
+      assert_match(/config\.active_storage/, content)
     end
 
     assert_file "#{app_root}/config/environments/production.rb" do |content|
-      assert_no_match(/config\.active_storage/, content)
+      assert_match(/config\.active_storage/, content)
     end
 
     assert_file "#{app_root}/config/environments/test.rb" do |content|
-      assert_no_match(/config\.active_storage/, content)
+      assert_match(/config\.active_storage/, content)
     end
 
-    assert_no_file "#{app_root}/config/storage.yml"
-
-    assert_file "#{app_root}/Gemfile" do |content|
-      assert_no_match(/gem 'mini_magick'/, content)
-    end
+    assert_file "#{app_root}/config/storage.yml"
   end
 
   def test_app_update_does_not_generate_active_storage_contents_when_skip_active_record_is_given