The autofill extension currently calls the success callback even if a
passcode/FaceID is not successfully verified.
In the case that the PGP key passphrase is stored, this results in
password decryption without further user interaction.
The fix is to only decrypt passwords upon successful passcode / FaceID
verification.
* Do not present lock view in 'viewDidLoad' since this might be too early for an extension ("Not running foreground").
* Instead, show it for actions requiring authentication, e.g. showing the password list or providing a password, or only in 'viewDidAppear'.
* Refactor and lazily load other view controllers and data.
* Let credential providing view controllers decide when to hide themselves.
