Attendees: focus search field after adding autocomplete item

Is your feature request related to a problem? Please describe.

The attendees tab in the event sidebar has a field to "Search for e-mails, users, contacts, resources or rooms". When typing a search term, it shows an autocomplete list with items that can be selected using arrow keys and confirmed using return.

After confirming/adding an item (e.g. a user), the search field loses it focus. This requires me to manually refocus the search field again with the mouse. This is tedious, especially for events with several attendees.

Describe the solution you'd like
After an attendee is selected from the autocomplete list, the search field should be focussed again.

Describe alternatives you've considered
(None.)

Additional context
(None.)

Start in the event sidebar's attendees tab and trace the search field and autocomplete selection flow. Reproduce selecting an item with the arrow keys and Return, then verify that the search field remains focused after the attendee is added and that repeated selections work without mouse refocusing.