Improve judging timer readability

[itamaroryan]

We have received feedback that the flow of the judging session (when to switch sections, what section is next) was not clear enough with the current timer.

Some ideas:

• Display a smaller general countdown and larger session countdown
• Display a flowchart that updates based on the current state to understand what comes next
• Display the timer for the current section as text instead of just the progress bar up to

We should choose which ideas would make the timer more readable, and implement them.

[itamaroryan]

Completed in #959