Introduce interface to easily create/edit default slots
Create new CVs/warnings based on default slots (moved to #163)
Improve scheduler to use more of the available space (introduce "fullscreen" view?)
Directly visualize violations and warnings in scheduling view
Add reload button to scheduling view
To remove code duplication, this introduces a new version of the availabilities editor, too (this implements #93 (closed)). With this, all calendar inputs use a common fullcalendar v5. The new availability editor code can be reused for the default slot inputs.
