Implement a "Disable on this Site" button

[pde]

Back when HTTPS Everywhere first existed, it was feasible to manually disable rulesets if something on a was broken or potentially broken by HTTPSE. Unfortunately, that's no longer practical; on many pages (here's an example) the user is confronted with a crazy long list of rulesets, and disabling them all is both a lot of work, and probably not what the user wanted.

Instead, we should add a "Disable HTTPS Everywhere on this site" button (and maybe also a "Disable HTTPS Everywhere on this page" button) to the top of the menu. Then users can happily receive a one-click solution if we're breaking the page (or we might be, and they want to check).

[Hainish]

Closed via #16546