Show position in course queue for shared labs

Summary

In a shared lab, show the position in course queue as well as the position in the total queue.

Checklist

• The position in the course queue is shown
• This position updates without refreshing just like the overall position

Implementation details

We can show something like Position in queue: 10 (this already exists) and below Position in 'Introduction to Programming' queue: 2.

Don't forget to update the websocket code as well, so the new number updates.