tails-greeter: better administration password UI

Hook tails-persistence-setup’s update_passphrase_ui dynamic warning system in.

That is, add to the greeter’s admin password and confirmation entry process the same kind of UX than the one used in t-p-s to choose a passphrase: can’t be empty, must enter twice the same passphrase, etc.

Attachments

• Fix-for-5594-tails-greeter-better-administration-pas.patch
• 0001-Fix-for-5594-tails-greeter-better-administration-pas.patch

Parent Task: #8230 (closed)

Original created by @tails on 5594 (Redmine)