Issue #3473346 by christian.wiedemann, pdureau, b.khouy: Keep enum typing with SelectWidget

.../src/Functional/LayoutBuilderFieldFormatterRenderTest.php

src/Plugin/UiPatterns/Source/EnumSourceTrait.php

src/Plugin/UiPatterns/Source/SelectWidget.php

...st/components/test-component/test-component.component.yml

tests/src/Kernel/Source/SelectWidgetTest.php

tests/src/Traits/RunSourcePluginTestTrait.php

tests/src/Traits/TestDataTrait.php

tests/src/fixtures/TestDataSet.yml