Adds 22 DNS e2e subtests across 8 test methods covering: upstream
resolution (A, AAAA, multi-A), TCP mode, bypass rules, host mapper,
exchange failure (graceful error recovery), rate limiter wiring,
invalid query handling, and DNS over TLS (mode: tls).
Includes two authoritative DNS responders (UDP/TCP), a standalone
DNS query client, and a TLS DNS query script.
Adds 12 new HTTP handler test scenarios: HTTP connector (no-auth, auth, TLS
upstream), CONNECT tunnel (no-sniffing, bypass-403), probeResist (host, web,
file, knock), idleTimeout, and UDP relay over HTTP. Introduces
RunGostContainerWithFiles helper for mounting extra files into test containers.