feat(promises): Switch to coroutine based Promise

[kristijanhusak]

Summary

Update Promise class to use coroutines. This change will allow writing more readable async code by providing async wrapper where necessary (new Promise.async() method), removing the need for multiple next() chains.
Changes should be fully backward compatible, with removal of the few unused methods, like Promise.any, Promise.race and Promise.all_settled.

Checklist

I confirm that I have:

• Followed the
  Conventional Commits
  specification (e.g., feat: add new feature, fix: correct bug,
  docs: update documentation).
• My PR title also follows the conventional commits specification.
• Updated relevant documentation, if necessary.
• Thoroughly tested my changes.
• Added tests (if applicable) and verified existing tests pass with
  make test.
• Checked for breaking changes and documented them, if any.

[kristijanhusak]

@seflue @chipsenkbeil just a heads up about this change. It should not affect org-roam, but I'd appreaciate if you can confirm that nothing is broken.

[chipsenkbeil]

@kristijanhusak I'll try to take a look this weekend. Finishing up some work on neovim core.

Btw, just got some early portion of vim.ui.img landed, and working on buffer-local images next. Once they land, you might be interested in an addition to nvim-orgmode to support orgmode images in some fashion as part of the neovim 0.13 release whenever that happens.

[kristijanhusak]

Sounds good. I'm following the progress on that :)

Currently we use Snacks for images, but I'm definitely looking forward to using the built in api once it's ready.