Event-Selection UI on Recording is unusable

[MaZderMind]

As a Backend-User, I want to change the Event a Recording belongs to, without scrolling the complete list of Events. I want to be able to type part of the Event-Name or the Event-Slug and see only matching Events.

Akzeptanzkriterien:

• The huge Dropdown is replaced with a Autocomplete-Field
• At all times an Event mus be selected, it is not possible to not select an Event
• Upon save, the Recording is assigned to the selected Event