Room Booking: Expose Location in the UI

[ThiefMaster]

When rewriting room booking, locations pretty much became a second-class citizen in the user-facing UI (AFAIK we don't show it anywhere). This is fine in case there is only one location anyway, but if an instance has more than one, then the location should be visible, and having e.g. a filter to see only rooms in a given location would be useful as well.