Support for Gin out of the box

Problem/Motivation

The Gin admin theme → provides nice enhancements to content forms. It only supports nodes by default but it would be nice to be able to use it with Recurring Events.

Steps to reproduce

Proposed resolution

Gin Admin Theme provides hooks which can be implemented to register additional routes which should use the Gin content layout. While it is easy to implement this yourself it would be nice to have the support out of the box.

It would look something like this:

function recurring_events_gin_content_form_routes() {
  return [
    'entity.eventseries.add_form',
    'entity.eventseries.edit_form',
    // There is no direct add form for instances. They are always created in
    // relation to series.
    'entity.eventseries.add_instance_form',
    'entity.eventinstance.edit_form'
  ];
}

It is worth noting that implementing this hook does not result in forms automatically being rendered in the admin theme for users which does not have the necessary permissions to use this.

Remaining tasks

- Add a merge request with the changes.

User interface changes

See attached screenshots.

API changes

None.

Data model changes

None.