Promisify internals

[fregante]

Started as a lint but, given the overlap, I think it's best to promisify first. No need to lint code that won't exist.

Best reviewed without whitespace.

This isn't a complete promisification, it just includes @octokit/plugin-throttling.js and changes a few callbacks to promises to make it more readable, catch more errors and reduce code along the way.

Excluding the dependency change, this PR reduces our code by 129 lines 148 lines 🥳

[fregante]

I'll drop the async dependency as well

[denis-sokolov]

This is great, thank you! A few minor comments to resolve, but I love the PR.

[denis-sokolov]

Thanks for all the effort! And the commits in this PR are clear and atomic, thank you.

In my workflow once a PR is approved and no comments are outstanding, it’s up to the author to merge at their convenience. There may be reasons for delay: perhaps some more last-minute ideas pop up, or a merge needs an oversight for deployment or otherwise. So feel free to merge when convenient. Or let me know if you prefer a different workflow!

[fregante]

I’m glad to be of help! And I’m glad that Octokit had an elegant way to throttle the API that allowed this PR to actually make it faster.