DNSSEC/DANE Padlock wót Seb35

This extension adds a padlock or a key when the website has the security technologies DNSSEC or even DANE, in which case it is a sign the website cares particularly about the security.

It uses a DNS-over-HTTPS resolver, either a pre-defined one or a custom DoH resolver, but there are no calls to other API or server.

You may configure the level of alert you want: a discrete icon in the address bar, or, in case of error, a notification or even a plain-page warning.

This extension is based on a previous one, DNSSEC/DANE Validator by defkev under free license GPL 3; it was upgraded and a few features were added (a cache, a CSP, and internationalisation as of now).