I forked rayon to use rayon-style API with switchable parallelization backend

tk;dr: I forked rayon to allow switching parallelization library or disable parallelization. See par-iter and par-core.

Hi. I'm the creator of the SWC project. I've been using chili for SWC Minifier. chili is a parallelization library with a heartbeat scheduling algorithm. I found that it performs far better than rayon for my usecase. But it lacks an API like parallel iterators of rayon. Additionally, I need to use different parallelization library for next.js or rspack and disable parallelism for Wasm targets. So I forked rayon and named it par-iter. par-iter is based on par-core, which allows selecting rayon or chili for parallelism, or even disabling parallelism using cargo features.

I prefer to get it merged back to rayon so I filed an issue on the rayon issue tracker to ask if they are open to a such PR, but I don't think it's likely, considering the package name.

Any ideas, thoughts, and feedbacks are welcome!