Add hyperlinks in tor circuit display to show "more info" about relays

Adapted from ticket legacy/trac#15169 (moved):

I'm considering the idea of turning the IP address for each relay in the circuit display into a hyperlink that when clicked, opens a tab in the browser showing more information about that relay. Alternatives include:

1. Showing the atlas.torproject.org page or globe.torproject.org page for that relay. Of course, this might have privacy implications, so perhaps only the exit node IP address should be shown/hyperlinked? Both atlas and globe require JavaScript, so it can be awkward if content JavaScript is disabled in Tor Browser.

2. Extract the relay information from the control port and display it in a locally-generated tab. This would avoid requiring content JS, but would lack the pretty graphs of atlas and globe. Mike points out that if we were going to display our locally-generated tab in Tor Browser, we would need to sanitize any descriptor text to avoid XSS attacks. I see there is an ​HTML sanitizer utility built into Firefox.