Create an async htop

[mre]

What?

Rewrite htop in Rust using async/await.

Why?

Would be a lot of fun to learn how to create a "lazy" version of htop and find out about the limitations of the Rust crate ecosystem around cross-platform process monitoring.

How?

Find some crates for process monitoring and put them behind async/await to update each process status regularly and independently from other processes.