Add support for multiple setup on the same instance of the Setup-Reservation tool

[wou007]

For now we need to run a SR tool instance for every setup we have, when we want to add additional setups. However it seems to me that the most optimal solution is to add multiple setups to the same page. In the case that when you want to use a setup you can see other setups that might be available in a single overview. This seems preferable over looking at multiple setups on multiple instances.

This also allows for preventing a user to claim all setups at the same time. Unless we want to support peer to peer checking?

[InzeNL]

The most user-friendly would be to have it all on a single page. With reserving a setup, we can simply have the user select which setup to reserve.

For storing these, we can simply use multiple CSVs, one per setup.

In the "Upcoming reservations", we could show N amount of timelines, as shown in https://github.com/DavidBergevoet/Setup-Reservation/issues/8#issuecomment-2157827559, which, when clicked, open up more details about that setup