Issue #3327598 by Grimreaper: Fix tests, apply code quality tools, Update README.md

README.md

composer.json

layout_options.module

modules/layout_options_ui/README.md

modules/layout_options_ui/layout_options_ui.links.menu.yml

modules/layout_options_ui/layout_options_ui.module

modules/layout_options_ui/layout_options_ui.routing.yml

modules/layout_options_ui/src/Form/Settings.php

src/Annotation/LayoutOption.php

src/LayoutOptionPluginManager.php

src/OptionBase.php

src/OptionInterface.php

src/Plugin/Layout/LayoutOptions.php

src/Plugin/LayoutOption/ClassAttributeCheckboxes.php

src/Plugin/LayoutOption/ClassAttributeRadios.php

src/Plugin/LayoutOption/ClassAttributeSelect.php

src/Plugin/LayoutOption/ClassAttributeString.php

src/Plugin/LayoutOption/IdAttributeOption.php

...ayout_options_test/layout_options_test.layout_options.yml

..._bad_yaml/layout_options_test_bad_yaml.layout_options.yml