Fixes #19775 - Fix Layout/ExtraSpacing cop

Fixes #19787 - Fix Layout/SpaceAfterComma cop

Refs #22164 - use cheaper FactoryBot methods

• Refs #22164 - FactoryBot.build -> FactoryBot.build_stubbed

• Refs #22164 - FactoryBot.create -> FactoryBot.build

in
- test/unit/*
- test/models/shared/taxonomies_base_test.rb
- test/controllers/hosts_controller_test.rb

Fixes #19771 - Fix Layout/EmptyLineAfterMagicComment cop

Fixes #21424 - use factory_bot_rails

Fixes #20951 - Replace render :text with :plain

Fixes #12156 - Adds email configuration into Foreman settings

Instead using email.yaml, the email configuration
can be modified dynamically via settings.

Fixes #12543 - enable utf-8 encoding in email address

According to RFC 6532, the local part of an email address
can be non-ascii characters, and should support in utf-8.
The current email validation doesn't allow it,
so emails like Pelé@example.com and 我買@example.com are not supported

fixes #16557 - move tests into modern Rails layout

Models, controllers, mailers and helpers are now in test/ subdirs
matching app/ subdirs. Service, miscellaneous and old test/lib/ tests
are now in test/unit/ separated from models, which obsoletes the custom...