More flexible slotted labs
## Description
Slotted labs currently only allow consecutive, same-length time slots. There are many use cases where this should be more flexible.
## Todo
- Design a new time slot configuration and time slot viewing UI
- The user should have full control over where time slots are placed, but it should not be harder to use than the current implementation.
- The user should be able to view the created time slots, view who is in a time slot, kick people out of a time slot, delete a time slot, move a time slot, resize a time slot in time and capacity.
- Do iterative design: make design, show to users, edit design, repeat.
- Implement
## See also
https://gitlab.ewi.tudelft.nl/eip/labrador/queue/-/issues/671
https://gitlab.ewi.tudelft.nl/eip/labrador/queue/-/issues/638
https://gitlab.ewi.tudelft.nl/eip/labrador/queue/-/issues/633
issue