Add biometric/pin lock with database encryption

[PhilKes]

Closes #30

• New preference for enabling/disabling lock:

  notallyx_issues_30_1.webm

Note: If the user has no HW support for biometrics a Toast is shown. If the user hasnt setup biometrics/pin yet he will be navigated to the device settings for that

• User has to unlock on first app start and after device has been locked

notallyx_issues_30.webm

• When the user enables the lock the database is also encrypted

• For backups, if the lock is enabled the backups copy a decrypted database into the zip

• TODO:

• Preference for setting time after which the user has to unlock again?

• As you can see in the video when locking the device and then unlocking with the app immediately open again the Views are shown very briefly. I do not know why yet, since I change the Visibility of all views in onPause to INVISIBLEand only set it to VISIBLE again AFTER the biometric/pin prompt. No idea where this behaviour is coming from.

[PhilKes]

@CodeNomadHQ @ippocratis I will merge this and release another RC, would be nice if you could test this out a bit. If all is working fine for now, I would do the first actual release v6.0, also looking into releasing it on F-Droid

[CodeNomadHQ]

Sounds good! I’ll test it out today to check for any bugs.