Extend the upgrader to allow full (self) upgrade

I would be very nice to be able to have a few-clicks away full upgrade process (incuding downloading the upgrade, veryfing it and installing it). This could either upgrade to an other device, or preferrabily the source device.

An usecase for that is: someone got a Tails device created by a trusted party using “Clone and upgrade”, they trust it but never went through the manual verification and installation process and don’t know how to use them, so they end up using an outdated version.

Team: kurono (research, ? (implementation)

Blueprint: https://tails.boum.org/blueprint/Endless_upgrades/

Related issues

• Related to #11131 (closed)
• Related to #11627 (closed)
• Related to #8861 (closed)
• Related to #15281
• Has duplicate #5981 (closed)
• Blocked by #15277

Original created by @alant on 7499 (Redmine)