Add new registrant type through the UI

Probably this is something that should target 3.x. While it has always been possible to use multiple registrant types by creating them programmatically, some other parts of the UI need to be updated as well to make this usable from a site builder perspective. For example a dropdown should be provided in the event series form to choose which registrant form to use when registering for an event.

Created an issue for choosing the registrant in the UI: ✨ Allow to choose a registrant type when setting up event registration Active . I think the best idea is to implement that first, otherwise we risk that site builders will be able to add multiple registrant types without an obvious way to use them.

Probably this is not really needed, when a new event series type is added a new registrant type is automatically created. I'm thinking now that for most regular use cases this will be sufficient. If advanced users would like to allow site builders to create standalone registrant types they can unlock the add form in their own custom module.

I'm going to close this, let's focus only on use cases that are interesting for 80% of users and leave advanced cases for custom modules.