`editedBy` item sort option for group libraries

[dstillman]

Like addedBy, and can probably modify this block to support both createdByUserID and lastModifiedByUserID:

We don't have usernames in the dataserver DB, so the way we have to do this is super hacky, but it works. It also looks like we don't actually ever clear these tables, which isn't really a problem, but that also means we never update the usernames if they change. Using REPLACE instead of INSERT IGNORE should fix that, at a very minor performance cost.

The DB table is tmpCreatedByUsers, but that's fine — we don't need to rename it.