Show progress through circuits

[glamperd]

Related to ceremonies with multiple circuits:
The progress panel that appears while a user is contributing shows messages related to the step in progress. Only a few of these messages indicate the circuit that is being worked on, which means that for much of the time the user is not aware of which circuit is being worked on, now the progress being made.

Feature request: Show a progress bar indicating which circuits have been completed, and how many are left to go. Ideally the status of each would be displayed.