Expose site-wide anonymized ids to HTML module

Co-authored-by: Nate Hardison <natehardison@gmail.com>

@cpennington and @sefk, please.

This doesn't do a per-course secret and it doesn't generate a new unique hash per user, but today I was told this would be sufficient for our one course that needs this, for the time being. I can't afford to spend any more time on doing it right at the moment, so we'd like to pull this in and move on, and circle back around to building a general mechanism for anonymization later in the Summer.