Add privacy settings

It would be nice of Jami have these privacy settings:

• Screen lock
  Lock Jami access with Android screen lock or fingerprint

• Screen lock inactivity timeout
  Lock screen after inactivity a time limit (user can adjust this)

• Block screenshots inside the app

• Incognito keyboard
  User can request a incognito keyboard to disable personalized learning

Edit:

• Remove metadata from file
  Remove metadata from file before sending it to the recipient.