Can the connect room button be made available for sessions too?

**Is your feature request related to a problem? Please describe.**
In https://indico.cern.ch/event/1273211/timetable/?view=standard we have various rooms. The connect-room button for zoom only applies to the room defined at the top, which is not valid for the whole conference.

**Describe the solution you'd like**
I would like to have a button next to each room defined in each sessions, or alternatively a button valid for the considered time-slot (that's dangerous however).

**Describe alternatives you've considered**
What we did was to reset the location at the top each time we changed rooms. That caused some confusion about the location of the meeting.

Start by finding the existing Zoom connect-room button and the code that renders session room locations. Compare its current top-level-room behavior with session timetable data; done means each session room has a usable button without changing the displayed conference location.

Written by the indexing model from the issue text.