Fatal error if no udp threads but using quic

[mattyw]

Fatal error if no udp threads but using quic

If proxy.config.http.server_ports contains an entry to allow quic connections on a given port but there no udp threads ATS used to silently ignore these connections.

Given that this configuration isn't valid we raise a fatal error.

We also raise a fatal error if quic is listed in server ports but ATS was built without quic support.