Add a list of public jobs

[psybers]

Right now users can mark jobs as public, but they must manually share the URL. It would be nice to have a list somewhere that shows the publicly available jobs. Perhaps something similar to how this page works:

https://data.stackexchange.com/

[psybers]

We may need other mechanisms for sharing jobs. I find myself often marking queries 'public' just so I can share with a team member. That doesn’t necessarily mean I wanted it ‘public’ per-se, it was just the only way currently to share with non-admins.

[psybers]

This issue is related to #3 in the sense that if we make a list of public jobs, it might be nice for people to add descriptions to them.