A leaderboard for scores (individual vs team based)

A suggestion from Zhansulu!

- Would need a mechanism to mark correctness #7
- Would need a mechanism to keep track of scores for participants who has used a name upon signing into a session
- Would need another pop out for leader board (Should be very similar in essence to results of polls)

Start by inspecting the repository entry points to find how correctness, session sign-in names, poll results, and pop-out views are currently handled. Break the work into correctness tracking, persistent participant scores, individual versus team modes, and a leaderboard view. Done means scores are updated for signed-in participants and displayed in a poll-like leaderboard for both modes.

Written by the indexing model from the issue text.