When restoring from backup do not ask for passphrase if device is unprovisioned
An unprovisioned device doesn't have any users, also not the initial admin user.
When restoring an unprovisioned device from backup, which has a config that defines an "admin" user (in the Administrator group) without passphrase, nethsm
still queries the user for the passphrase.
Instead we should check up front whether credentials are actually needed (e.g. with one of the nethsm health
calls) and not ask for passphrase or user if the device is unprovisioned.