[Rust] Parallelize simulations

[bugarela]

One simulation is independent of the other. It should be straightforward to run them in parallel. The goal would be to use multiple cores so users can check more samples in the same amount of time. We should be careful to not run all parallel instances with the same seed - there's no point checking the same sample more than once.

[konnov]

You don't need rust to do that. Here is how you can do that with GNU parallel: https://github.com/matter-labs/era-consensus/blob/main/spec/protocol-spec/experiments/quint-verify-parallel.sh. This script parallelizes calls to Apalache, but you can do the same with the simulator. The delay of 1 second kind of helps to produce different seeds. If you want to be on a safe side, you could explicitly set the seeds to different values using the job number.

[bugarela]

Sure, I'm also using GNU parallel for all sizeable projects, but now that we have an evaluator in Rust, we can make this seamless for the users. Your script seems to have slightly better UI than what I was doing here, but still, I'm sure the native support will be better for everyone 😄