Consider simplifying async usage

[LesnyRumcajs]

Summary

Inspiration material: https://www.youtube.com/watch?v=lJmRf9EejU4&list=PL8NC5lCgGs6MnMLJvhFH2jLa8bLYwCzmI&index=12

The gist of this is that we could potentially improve readability of the code without impacting performance (it might even fare better) if we explore some options:

• using https://docs.rs/moro/latest/moro/macro.async_scope.html instead of putting Arc's everywhere
• switching to some thread-per-core strategy; this would ease lots of constraints on Send that we have internally, potentially simplifying code and improving performance as well (less synchronization mechanisms). Not sure if it's possible with tokio, there's https://github.com/DataDog/glommio but it'd be huge amount of work to refactor things given our frequent usage of tokio utils.

Completion Criteria

• Investigate either of the approaches and see if it brings any benefits; the first one with moro should be a quick win

Additional Links & Resources

https://emschwartz.me/async-rust-can-be-a-pleasure-to-work-with-without-send-sync-static/

[LesnyRumcajs]

I investigated moro async_scope, it doesn't seem to be worth it.

[LesnyRumcajs]

switching async runtimes seems like an overkill and kind of a precedent, not done a lot in the ecosystem; not worth the hassle.