[Tails-dev] [review'n'merge:1.2] feature/tor-browser-4.0

Hi,

Please review and merge (Git and APT) into devel and testing.

Closes:

* #8058 - Upgrade to Torbutton 1.7.0.1 final
* #8026 - Update to Tor Browser 4.0

(BTW: For conflict resolution with the stuff from
feature/8031-refactor-10-rbb-hook, have a look at how it was done for
experimental in commit 1e9e1442e4b3ad8e82492ebd2d856ec45c02a884)

Cheers!