vquic: stabilization and improvements

vquic: stabilization and improvements

vquic stabilization
- udp send code shared between ngtcp2 and quiche
- quiche handling of data and events improved

ngtcp2 and pytest improvements
- fixes handling of "drain" situations, discovered in scorecard
  tests with the Caddy server.
- improvements in handling transfers that have already  data or
  are already closed to make an early return on recv

pytest
- adding caddy tests when available

scorecard improvemnts.
- using correct caddy port
- allowing tests for only httpd or caddy

Closes #10451