osslclient and osslserver are the ngtcp2 example
client and server; the devcontainer image builds them from upstream and installs them as
/usr/local/bin/osslclient and /usr/local/bin/osslserver. A few small helpers from the
same examples live in anyhttp/h3_common.hpp.
osslserver ::1 8080 pki/out/server-key.pem pki/out/server-chain.pemcurl --http3-only --cacert pki/out/root.pem https://[::1]:8080/CMakeLists.txt -vv