Issue #3479843 by pfrenssen: Adhere to coding standards

.gitlab-ci.yml

.../recurring_events_ical/tests/src/Kernel/EventICalTest.php

...events_registration/recurring_events_registration.api.php

modules/recurring_events_registration/src/AccessHandler.php

...ents_registration/src/Controller/RegistrantController.php

...s/recurring_events_registration/src/Entity/Registrant.php

...ing_events_registration/src/Form/RegistrantDeleteForm.php

...recurring_events_registration/src/Form/RegistrantForm.php

...g_events_registration/src/Form/RegistrantSettingsForm.php

...gistration/src/Plugin/ComputedField/AvailabilityCount.php

...gistration/src/Plugin/ComputedField/RegistrationCount.php

...s_registration/src/Plugin/ComputedField/WaitlistCount.php

...n/src/Plugin/views/access/EventRegistrationListAccess.php

...vents_registration/src/RegistrantAccessControlHandler.php

...g_events_registration/src/RegistrationCreationService.php

...rring_events_registration/src/Routing/RouteSubscriber.php

...egistration/tests/src/Kernel/RegistrantControllerTest.php

recurring_events.api.php

recurring_events.module

src/Controller/EventInstanceController.php