Introduce model (including migration and admin interface)
Integrate into new event wizard
Display as property in details representation (e.g., used in scheduler)
Allow to choose types in AK add/edit forms
Show type info on AK detail page and in overview table
Adjust tests (including new tests for requirement and type visibility in submission form)
Update translations

Add docstrings
Remove code-duplications for dispatching user selection on submission overview
Remove code smells
Remove unused admin.py
Remove unused view in views

Add a new link to edit form leading to owner creation form and passing the primary key of the edited AK/wish to that view
To realize that link, the corresponding field is excluded from the default form rendering and the rendering is triggered manually for that field (and the name field that should still appear on top)
When user is successfully created, they is set as owner of an AK, the user is redirect to the detail page of that AK and a message is displayed
Add corresponding test
This implements #96 and #86

Fix issue detected while creating test

This includes a new helper method to assert the existence of a particular message