Update __wasi_sock_accept signature to match wasi_snapshot_preview1 (#1531)

The function was introduced to WASI about half a year ago after it already
existed in WAMR.

It caused problems with compiling `wasi_socket_ext.c` with the wasi-sdk
that already had this hostcall exported (wasi-sdk >= 15).

The approach we take is the following:
- we update WASI interface to be compatible with the wasi_snapshot_preview1
- compilation with `wasi_socket_ext.c` supports both wasi_sdk >= 15 and wasi_sdk < 15
  (although we intend to drop support for < 15 at one point of time)
- we override `accept()` from wasi-libc - we do that because `accept()` in `wasi-libc`
  doesn't support returning address (as it doesn't have `getpeername()` implemented),
  so `wasi_socket_ext.c` offers more functionality right now

Resolves #1167 and #1528.

[1] https://github.com/WebAssembly/WASI/blob/main/phases/snapshot/witx/wasi_snapshot_preview1.witx

core/iwasm/libraries/lib-socket/src/wasi/wasi_socket_ext.c

@@ -140,7 +140,7 @@ accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen)
     __wasi_fd_t new_sockfd;
     __wasi_errno_t error;
 
-    error = __wasi_sock_accept(sockfd, &new_sockfd);
+    error = __wasi_sock_accept(sockfd, 0, &new_sockfd);
     HANDLE_ERROR(error)
 
     error = getpeername(new_sockfd, addr, addrlen);