Settings: privacy Guard ehance app logic

This commit changes the following

- do not show built in apps at all (like settings, systemUI, android system etc)
  IMO the user should trust the android signed apps to be save and this will
  prevent weird behaviours user can get when they activate it on this packages
  all other system apps (like calculator, browser and all which are not signed with
  android key are not effected.

- to go inline with AOSP disable the checkbox in detail app screen
  for built in apps

- reflect as well show system apps to the detail app screen

cheers

SlimRoms

Change-Id: I12b5522f6e58047173778381fb7290bb1c71bab3