Instead of manually iterating over netifs to find the one a packet came
in over for NetBIOS name lookup, use a built-in LWIP macro that's
available for udp_recv callbacks. Shrinks and simplifies NetBIOS code.
Thanks to @me-no-dev's code. Lets Windows look up the PicoW by name
using NBNS and needs much less memory and code than mDNS.
AsyncUDP ported from the old ESP8266 version, only minimal changes. Will
probably only be valid in IPv4 environments and may not match current
ESP32 AsyncUDP interfaces.