Force HTTP/1.1 ALPN for websocket TLS

[fannnzhang]

Summary

• thread a websocket-specific TLS ALPN hint through call context
• make the Rustls connector force http/1.1 ALPN for websocket TLS handshakes
• add focused regression coverage for websocket handshakes against servers that prefer h2

Validation

• cargo test -p openwire --features websocket websocket_tls_uses_http11_alpn_when_server_prefers_h2 -- --exact
• cargo test -p openwire-core
• cargo test -p openwire-rustls
• cargo test -p openwire --features websocket injects_websocket_handshake_headers --lib