add https_only, started from Firefox 76

[dimon4ezzz]

i guess https_everywhere should be removed

[dimon4ezzz]

Please, add advanced description to help_text field

[allo-]

HTTPS everywhere switches to HTTPS when it is available.
This option shows a warning for unencrypted connections like for SSL errors.

This probably belongs to a secondary profile like #50 (Paranoid) or #114 / #112 (Harden HTTPS).
I think I would not like to include it in the main profile, because it sounds like a good option, but (almost) breaks a lot at the current state of the web.

I still would like to allow the user to merge profiles, so he can use "default+harden https" to see the standard options and the options that break sites without https / with outdated encryption standards.

[Madis0]

For now this would belong to Paranoid, yes. I hoped that Firefox could include something like HTTPZ, which would attempt HTTPS first but also fallback automatically when needed.

[allo-]

HTTPZ may be worth to be included as addon. I need to try it, but when it's lightweight enough it would be a nice security improvement.

[dimon4ezzz]

cannot be used after Firefox 91, where HTTPS-First setting was introduced