All existing DHCPv4 packages I looked at were unappealing for one reason or
another, so we’re now using a little helper to glue github.com/google/gopacket
and github.com/mdlayher/raw together, which suffices for our use-case and gives
us more control.
This makes them complete more quickly (because they are run in parallel) and
invalidates only the cache for the integration test I’m working on, not for all
of them.
