Add a prompt right before applying an IUK

Originally created by @anonym on #15282 (Redmine)

Downloading an IUK can take a long time (up to hours) so users will likely use Tails for other purposes meanwhile. However, the current behavior is to abruptly disable the network as soon as the IUK is downloaded, possibly breaking work for them.

Therefore we should add a prompt after the download. It should make it clear that once you close the prompt, the network is cut. I think it would be good that it also encouraged users to close all applications they have started to free some RAM for the IUK installation.

Feature Branch: bugfix/14754-partially-applied-upgrades, iuk:bugfix/14754-partially-applied-upgrades

Attachments

• before
• after

Parent Task: #15281 (closed)

Related issues

• Related to #14754 (closed)
• Blocks tails/accounting#15506