Support WASIp2 sockets in read and write

[dicej]

Currently, you can use recv and send to read from and write to WASIp2 sockets, respectively, but neither read nor write work. We should support those functions as well, using logic analogous to what we have in close, where we check whether the file descriptor is a WASIp2 socket and defer to the appropriate function if it is:

wasi-libc/libc-bottom-half/sources/__wasilibc_fd_renumber.c

Lines 78 to 95 in b9ef79d

	#ifdef __wasilibc_use_wasip2
	descriptor_table_entry_t entry;
	if (descriptor_table_remove(fd, &entry)) {
	switch (entry.tag)
	{
	case DESCRIPTOR_TABLE_ENTRY_TCP_SOCKET:
	drop_tcp_socket(entry.tcp_socket);
	break;
	case DESCRIPTOR_TABLE_ENTRY_UDP_SOCKET:
	drop_udp_socket(entry.udp_socket);
	break;
	default: /* unreachable */ abort();
	}
	return 0;
	}
	#endif // __wasilibc_use_wasip2

(Note that whereas we use descriptor_table_remove in the close implementation, we'll want to use descriptor_table_get_ref in the read and write implementations.)