Changed the IPv6 support detection to try multiple common ports (HTTP/HTTPS) instead of
just testing against a DNS port. The function now returns both the IPv6 support status
and the successful port that confirmed the connectivity. This makes the IPv6 detection
more reliable by not depending solely on DNS port availability.
Previously, the function only tested connectivity to a DNS port (53) over IPv6.
Now it tries to connect to commonly available ports like HTTP (80) and HTTPS (443)
until it finds a working one, making the detection more robust in environments where
certain ports might be blocked.
On Windows host with StarLink network, ctrld hangs on startup for ~30s
before continue running. This dues to IPv6 is configured but no external
IPv6 can be reached. When probing stack, ctrld is dialing using ipv6
without any timeout set, so the dialing timeout is enforced by OS.
This commit adds a timeout for probing dialer, so we ensure the probing
process will fail fast.
