Add or complete docstrings
Remove code smells
Disable irrelevant warnings
Update translations to changed line numbers and line breaks
Move duplicated code for event field pre-population and event timezone adaption to mixins

This used the common fullcalendar v5 instance instead of a special v3 version only for this editor
Improve visualization of availability deletion
Improve (event specific) timezone handling and remove dependency to moment-timezones

availabilities in AK submission
availabilities in AK wish submission