Worker implementation selection

[yurynix]

Hi 👋
Thank you for the great library! 🙏

When moving from 1.x to 2.x, the implementation of the workers was switched from process (child_process) to threads (worker_threads), which is great for many workloads, however, for some workloads, processes are preferred.

Specifically what bothers me is workloads that do process.chdir() which is not supported inside worker_threads.

Would you be open to a new option in WorkerNodesOptions -> .workerType which can get thread (default) or process,
that will control the underlying implementation?

I don't think it's a big code change, however one downside is that WorkerNodesOptions.resourceLimits is only going to be supported in worker_threads.

What do you think? 🙃

[yurynix]

@bgalek what are your thoughts on this? 🙃

[bgalek]

@yurynix if we leave worker_threads as a default I'm ok with providing option to change thread to process ;)

[yurynix]

Cool, so I'll draft a PR next week 🙏