fixup! Bug 27476: Implement about:torconnect captive portal within Tor Browser

Depends on torbutton!81 (merged)

New tab goes to about:newtab now rather than about:tor or about:blank explicitly, so we need to add a check for handling the about:newtab case

fixes #40752 (closed)

Supersedes !240 (closed) (this version is rebased against 91.5.0 11.5-1)