Update bridges

Three of our four obfs4 bridges are no longer reachable.

This branch replaces the three unreachable bridges with 12 Tor Browser bridges from https://gitweb.torproject.org/builders/tor-browser-build.git/tree/projects/tor-browser/Bundle-Data/PTConfigs/bridge_prefs.js, skipping one Tor Browser bridge that's unreachable and one that has an IPv6 address, since we haven't had a chance to test IPv6 obfs4 bridges yet.

The dummy address of the meek bridge is also updated - see https://gitweb.torproject.org/builders/tor-browser-build.git/commit/projects/tor-browser/Bundle-Data/PTConfigs/bridge_prefs.js?id=8bd845464ae14bf56e0187dfa6f6e773a6593f55 for an explanation.

A run configuration for BridgeTest (which is skipped by default) is added.