Smarter bootstrapping for Tor Browser taking censorship into account

Right now we don't offer the user much help when connecting wherever they are with their mobile phone. They get to make the choice to be on the safe side given their current context as to whether they want to connect directly or use a bridge/PT.

However, we might be able to be smarter here and make at least suggestions or allow even some bridge selection behind the scenes helping with a more automated bootstrapping.

The desktop related tickets are legacy/trac#21951 (moved) and legacy/trac#24527 (moved).

See for a good summary on what the Briar folks do (with further links to tickets on their side): https://lists.torproject.org/pipermail/tor-dev/2019-February/013708.html.