Allow to add a break to EVERY room

[rixx]

Discussed in #1731

^{Originally posted by navlisilvan April 5, 2024}
We have a schedule with 13 rooms.
When adding a "Lunch"-break, we have to add the break 13 times to all the 13 rooms.
It would be great if there would be an option to add the break to all rooms at the same time.

Thanks a lot!