UX fixes for ESR91 Tor Browser
A parent ticket to keep track of all the UX breakage we'll need to take care of in ESR91 based Tor Browser:
- updated icons (new builtin icons are all have thin lines now): identity-block onions, security settings icons, new identity, thinner onion icon branding
- circuit display will probably break/need tweaks
- security level door-hanger may need to be tweaked/restyled
- probably fixes in about:torconnect and the v2 onion warning page (both depend on about:neterror)
- possibly fixes in about:preferences#tor (tor logs, bridges dialogs)