[Request] Add checks for ECH and WebRTC leaks

[ParticleMon]

More possibly useful tools would be checking for ECH and WebRTC leaks to eliminate using other tools such as:
https://defo.ie/ech-check.php
https://www.cloudflare.com/ssl/encrypted-sni
https://mullvad.net/en/check

[brianshea2]

dnscheck.tools already performs WebRTC-based IP detection. Although, maybe I should add some type of indicator for such IPs or add an advanced section to show all the detected candidates (these are logged to the javascript console in dev tools currently if you want to see them).

ECH detection is a good idea but I'm not sure it belongs on dnscheck. I've had some TLS parameters reported on the header-echo tool but have since removed them to simplify it. Maybe it's time for a new tls-dump or similarly named tool to show the TLS handshake process.