Update documentation for Wayland

Tasks

• Developers give technical writers a list of user-facing changes brought by !838 (merged)
• Update end-user documentation
  • doc/first_steps/welcome_screen/administration_password (at least the part that mentions #12213 (closed))
  • doc/anonymous_internet/unsafe_browser/security_implications.inline (at least the part that mentions #12213 (closed))
  • wiki/src/doc/anonymous_internet/tor.mdwn (the part that mentions #18219 (closed))
  • xorg-driver= and nomodeset workarounds are not relevant anymore (and they even break the boot, at least on some machines; see #19321 (closed) for details): a37c5535
• Consider making the recommendation to close the Unsafe Browser stronger (!956 (comment 199070))

User-facing changes

• Tor Browser, Thunderbird, and the Unsafe Browser now run as native Wayland applications ⇒ better security. But this may cause some small but annoying UI bugs as of Tor Browser 11.5 (based on Firefox 91), which are fixed in Tor Browser 12 (based on Firefox 102), which should be released before 5.8
• Wayland (#12213 - closed)
• Make our test suite compatible with Wayland (#19042 - closed)
• Tor Browser sandbox breakout via X11 testing ex... (#14623 - closed)
• The Unsafe Browser allows to retrieve the publi... (#15635 - closed)
• Make the Unsafe Browser work on Wayland, somehow (#19008 - closed)
• No audio in Unsafe Browser breaks accessible CA... (#16795 - closed)
• Make the Unsafe Browser run by the amnesia user... (#18020 - closed)
• Captive portals that require uploading a file d... (#17284 - closed)
• Sandbox the Unsafe Browser (#5422 - closed): the Unsafe Browser now runs in isolated mount and network namespaces, and is confined with AppArmor (let's not boast about it too much though, it's still quite weak isolation, future improvements are tracked on #19212)
• IBus input methods cannot be used in the chroot... (#9767 - closed)
• Unsafe Browser is not accessible (#7502 - closed)
• Open the Unsafe Browser from Tor Connection (#18339 - closed)