Support bundles that aren't provided by entity types, add tests.

.travis.yml

entity.module

src/Controller/EntityCreateController.php

src/Routing/CreateHtmlRouteProvider.php

tests/Functional/CreateUITest.php

tests/Kernel/EntityRevisionLogTraitTest.php

tests/Kernel/RevisionBasicUITest.php

...y_module_test/config/schema/entity_module_test.schema.yml

...les/entity_module_test/entity_module_test.permissions.yml

.../modules/entity_module_test/src/Entity/EnhancedEntity.php

...es/entity_module_test/src/Entity/EnhancedEntityBundle.php