Extend MASQUE implementation to support TCP tunneling via standard HTTP/3
CONNECT method, in addition to existing UDP support via CONNECT-UDP:
- Add StreamConn type for TCP data transfer over HTTP/3 stream body
- Update handler to dispatch based on :protocol pseudo-header:
- "connect-udp" for UDP (RFC 9298)
- Empty/"HTTP/3.0" for TCP (RFC 9114)
- Add handleConnectTCP() using bidirectional stream relay
- Update connector to support both TCP and UDP networks
- Add connectTCP() for standard CONNECT requests
TCP uses :authority for target address and stream body for data.
UDP uses path template and HTTP/3 datagrams for data.