packages: settings: CryptKeeper: Disable FDE if PFE activated

Don't allow Full-Disk-Encryption (FDE) after Per-File-Encryption (PFE)

Change-Id: I5ed46d4362f6536a6cf526aa5bf4bac4610c47b6
Settings: fix a couple of multiuser bugs

- show interface settings
- hide media scan on boot behaviour
- show privacy guard

for other users

Change-Id: I2b488f69b820f289d7ddb04e5171637b355dc5cf