Add support for Tokio Command

[itpetey]

[igalic]

and what does that do?

[itpetey]

Tokio Command? It's an async version of the std lib, which sits on top of Tokio's runtime.

https://docs.rs/tokio/1.28.2/tokio/process/struct.Command.html

[asomers]

What primitives does it use? I guess it probably uses asynchronous pipe APIs for stdin and stdout. But does it spawn a thread for wait or use kqueue's EVFILT_PROC to detect when the child has exited?

[itpetey]

I'm not a Tokio dev, so I don't know what's under the hood. However I do know that Tokio sits on top of Metal I/O, which explicitly supports FreeBSD: https://github.com/tokio-rs/mio.

[fabianfreyer]

LGTM!