[Queue] Enable COVID Mode

[amandaLi7]

Right now, we can set locations to be specific rooms. We have the Join Zoom button regardless of if we're virtual/in-person, which can get confusing.

1. Add a COVID Mode in Admin settings (?) to enable it. this entails setting:

• TA's zoom room as default and only location in student entry.
• Adding Join Zoom button in the "Ta is helping!" box for students

3. Remove the Join Zoom button for when COVID Mode is not enabled