Add HTTP/2 Sever-side Support
- Add HTTP/2 support on the server side.
- Send HTTP header fields in the order specified in the YAML file.
- Test: use get_port to dynamically grab open ports during AuTest execution.
- Update to build with libswoc 1.2.17 and use its new Errata and Rv features.
- Test: Remove the pyOpenSSL pin for the AuTest Python virtual environment.
- Bug fix: fix handling of zero-length chunked bodies.