Limit the number of apps running as system user

For the system user, enable apps based on the following conditions:
- app has no launcher icons or has INTERACT_ACROSS_USER_FULL permission
- app is whitelisted
- app is not in the blacklist

Bug: 23283899
Change-Id: I90fa266e8cfb28d002e5f792998fdddb6a1e6969
7 files changed