Refined-github: Add PR review filter "Not reviewed by you"

[dertieran]

I often have the issue that some PRs are still pending review by other contributors,
but I want to just see the PRs I haven't reviewed yet.

There is a "Reviewed by you" option, but I want the negation of this

This can be achieved by prefixing the reviewed-by:USERNAME parameter with a -,
so e.g. -reviewed-by:DerTieran.

I'm happy to implement this functionality if it is wanted.
My idea would be to add the "Not reviewed by you" filter item to the above drop down menu.

[dertieran]

Okay I just hacked something together that works (you can find it here)
(Comments/Commits will be cleaned up before I open the PR :smile:)

There are still some issues, mainly that Github thinks -reviewed-by is the same as reviewed-by and checks the "Reviewed by you" option.

If someone here finds the time, I would be happy if someone could look over the code and tell me if I'm on the right track.

Thanks for that in advance.

[busches]

Looks pretty good, I'd open a PR and get official feedback and testing.

[lukehefson]

Heads-up that we added this natively to GitHub! https://github.blog/changelog/2019-03-18-view-pull-requests-not-reviewed-by-you/

❤️ 💛 💜 💚

[fregante]

We pre-emptively removed it in #1831 😅 (the feature worked for all dropdowns)