Make regrade status of a submission more clear

[jhs-panda]

Requested by 15213.
Currently, when a submission is regraded, TAs are unable to tell what the status of the regrade is since it only displays a score (can't tell if still regrading or if autograder finished running already and score did not change).
Proposed solution: Better visual indicator for submissions that are still being regraded (ex. clock symbol to replace scores while being regraded)

[20wildmanj]

Adding on from 122, they recently had an issue where they could not easily figure out the progress of regrade all. That makes sense. It is totally possible that I clicked "regrade all" twice given that, like many things on Autolab, there is no visual feedback that something is happening until the relevant page gets loaded, which can take a while. (For "regrade all", that's typically an error page several minutes in -- but we've learned that it's not a real error, just the GUI timing out or something).

Note: Technically, they are able to see the progress via the jobs page but they might not be checking that? Also, I guess this does not really give a "progress" indication, especially if there are other jobs executing for other assessments, it just tells you which jobs are in the queue and which are running.