[Assignments] Remove metadata from downloadable assignment submissions

Problem statement:

Currently if an assignment is marked for anonymous grading, Canvas does successfully cloak the student's name within Canvas. However, if the submission file is downloaded, its metadata is still in it and the original 'author' of the file can be seen, either intentionally by clicking to view the file's details or accidentally by simply hovering the mouse cursor over the file. This defeats any anonymity. If it was just faculty downloading assignments, we could advise them how to avoid this to the best of their ability, but in the case of peer review assignments we have much less control over students using classmates' information in negative ways. As it stands, we have had to discourage our faculty from using the anonymous grading feature on peer review assignments.

Proposed solution:

I'd like to suggest that when assignment submissions are uploaded to Canvas, the file somehow be stripped of any metadata. Or at the very least, that a disclaimer be added to the assignment settings page so faculty will understand the risk before turning it on.

User role(s):

admin,instructor,student,ta