Use `synckit` to simply and support other features like yarn PnP and experimental loader

[JounQin]

I'd like to raise a PR if you agree.

See also

• https://github.com/un-ts/synckit
• feat: support yarn PnP out of box, propagate PnP runtime un-ts/synckit#98
• fix: pass yarn PnP experimental loader to worker if it exists un-ts/synckit#103

Besides, I'm trying to make synckit work on browsers with Web Workers at un-ts/synckit#31.

[fisker]

No, thanks. But we may want try it if PnP support is requested.

[JounQin]

That's OK.

[rattrayalex]

FWIW, this repo did not work for me – it just hung, without printing anything, even in a REPL – and using synckit with the next branch of prettier did work for me. Performance was not too bad either.