Admins can currently add the bookmarks discovery route link
to the homepage interface, but users can't presently select
that as their default home view. This change facilitates that,
adding the option to the existing Default Home Page dropdown on
the User Preferences Interface page.
This helps us out in a few ways:
1. It lessens our reliance on jQuery
2. It's slightly less code because it omits options we don't use
3. It is one less library to import and put into ES6 modules
This reverts commit 20780a1eeed56b321daf18ee6bbfe681a51d1bf4.
* SECURITY: re-adds accidentally reverted commit:
03d26cd6: ensure embed_url contains valid http(s) uri
* when the merge commit e62a85cf was reverted, git chose the 2660c2e2 parent to land on
instead of the 03d26cd6 parent (which contains security fixes)
