Disconnect comment links fom the WebUI

[da2x]

rel=noopener results in better performance and security for untrusted links. Implicit in very-up-to-date browsers, but people still use older browsers through embedded webviews in apps and devices. rel=noreferrer ever so slightly enhances user privacy.

[Chocobo1]

We specified our supported browsers here: https://github.com/qbittorrent/qBittorrent/tree/master/src/webui/www#browser-compatibility
Although within this range some older browser isn't applying the action by default yet the browser will soon be outdated... personally I won't be active to support this PR unless others think it is a necessity.

Implicit in very-up-to-date browsers

Also note that it is in the spec: whatwg/html#4330

[Piccirello]

This is a small change but probably worth it. I suspect there shouldn't be any additional work to support this beyond the initial commit. If the team ultimately decides not to merge this, that's probably ok too.

[Chocobo1]

@da2x
Thank you!