Implement the remaining socket-related WASI functions. (#4776)

* Implement the remaining socket-related WASI functions.

The original WASI specification included `sock_read`, `sock_write`, and
`shutdown`. Now that we have some sockets support, implement these
additional functions, to make it easier for people porting existing code
to WASI.

It's expected that this will all be subsumed by the wasi-sockets
proposal, but for now, this is a relatively small change which should
hopefully unblock people trying to use the current `accept` support.

* Update to system-interface 0.22, which has fixes for Windows.

crates/wasi-common/README.md

@@ -32,14 +32,7 @@ Please note that the library requires Rust compiler version at least 1.37.0.
 
 ### *nix
 In our *nix implementation, we currently support the entire [WASI API]
-with the exception of socket hostcalls:
-- `sock_recv`
-- `sock_send`
-- `sock_shutdown`
-
-We expect these to be implemented when network access is standardised.
-
-We also currently do not support the `proc_raise` hostcall, as it is expected to
+with the exception of the `proc_raise` hostcall, as it is expected to
 be dropped entirely from WASI.
 
 [WASI API]: https://github.com/WebAssembly/WASI/blob/master/phases/snapshot/docs.md