virtual TCP/UDP loopback

[rvolosatovs]

This PR introduces a virtual wasi:sockets loopback, which is isolated from the OS and is implemented in-process.

With this changeset:

• workload components cannot bind on any IP using TCP
• workload components cannot connect to OS loopback using TCP
• workload services can bind on either loopback (virtualized) or unspecified IP using TCP. Bind on unspecified IP will use the TCP port on the OS. Services can receive TCP packets destined for OS localhost (or whatever corresponds to unspecified IP on the OS) by binding and listening on unspecified IP.
• workload components/services can bind on either loopback (virtualized) or unspecified IP using UDP. Bind on unspecified IP will use the UDP port on the OS. Both components and services can receive UDP packets destined for OS localhost (or whatever corresponds to unspecified IP on the OS) by binding to unspecified IP.
• workload components cannot send packets to OS localhost using UDP

wasmtime-wasi is copy-pasted into this repo and modified. The actual loopback implementation is in this commit: f7bc41b

Before release to crates.io, the patch section has to be removed from Cargo.toml (it should stay on main, however, such that we could test wash-wasi)

This PR must not be squashed