Password protected handout/assessment downloads

[nayak16]

We want to password protect handout downloads with a unique password for each user based on their email. V2 will be custom password generators so instructors can specify how to match and verify passwords.

Suggested by Seth Goldstein (213 professor at CMU)

[zyx-billy]

I wonder if this could be done with custom listOptions for an assessment. There doesn't seem to be any documentation on it, but 213 bomblab uses listOptions to display a custom 'Download your bomb' option on the sidebar of an assessment.
It seems at the very least, it could support any custom link. We can easily make it more powerful by sending the username in the query params, and/or asking the user for a passphrase and sending that along with the request as well. This way, the instructor can setup a simple server somewhere else that does whatever they want.