quic: more quic refactorings and cleanups

Builds on https://github.com/nodejs/node/pull/34262 ... that one needs to land first (the first three commits are from that PR)

• quic: replace ipv6Only option with 'udp6-only' type

  Since the ipv6Only option was mutually exclusive with using 'udp6', making it it's own type simplifies things a bit.

(more will be added)

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines