Merge "Delete persistent volume" and "Configure persistent volume"

Originally created by @sajolida on #17331 (Redmine)

We should have a single menu entry called “Persistence”:

• When there is no Persistence, it would create one.
• When there is Persistence and it’s unlocked, it should open the configuration.
• When there is Persistence and it’s locked, it should display something like this:

Tails was started with Persistence disabled.

Restart Tails and unlock Persistence to use its content.

[Delete Persistence] [Restart Tails]

With after that a scrary confirmation warning with a red button and everything:

Deleting Persistence will delete all your data:

* Persistent folder
* GnuPG keys
* Thunderbird emails
* etc.

This operation cannot be undone.

[Cancel] [Delete Persistence And Loose All My Data]

Related issues

• Related to #14544 (closed)