Field inheritance working nicely, added instance settings form

recurring_events.links.menu.yml

recurring_events.links.task.yml

recurring_events.routing.yml

src/Entity/EventInstance.php

src/Entity/EventSeries.php

src/EventCreationService.php

src/EventInstanceListBuilder.php

src/Form/EventInstanceSettingsForm.php

src/Form/EventSeriesSettingsForm.php

src/Plugin/FieldInheritance/FieldInheritancePluginBase.php

src/Plugin/FieldInheritance/TextFieldInheritancePlugin.php

...lugin/FieldInheritance/TextLongFieldInheritancePlugin.php