Disable networking

[haraldng]

As discussed in the dev-sync this week, it would be nice to let users disable networking at compile-time if they only intend to use Kompact locally.

[Bathtor]

I anyway discussed with @adamhass before that we should move networking into it's own crate. That'll make it easy to hide it behind a compile time flag. So +1 from me.

[segeljakt]

This will also allow Kompact to compile into WebAssembly 🤩