Add a "sponsor" flair to usernames on Github Issues and Pull Requests

[zachriggle]

While I don't expect any special treatment for being a sponsor -- I'm a sponsor because I want to support the work, not to get priority -- it would be neat if we could show some kind of flair next to the username on PRs and Issues.

I think that increasing the visibility of sponsors on a project will encourage others to do so. In the below images, you see the team affiliation of a Github member with a project. I think something similar for Sponsor would be neat.

Maybe add a ⭐️ if you're feeling snazzy.

Additionally, I think it would be useful if the Sponsor bubble / label / etc were clickable (or hover-and-expand) to give a link to viewers to make it easy for them to become a sponsor.