Add getDisallowedSystemApps to DevicePolicyManager

- The getDisallowedSystemApps is based on OverlayPacakgesProvider which
  is moved from ManagedProvisinoing
- getDisallowedSystemApps will be used by ManagedProvisioning
- createAndManageUser will now use getDisallowedSystemApps to disable
  disallowed system apps when creating users
- LEAVE_ALL_SYSTEM_APPS_ENABLED can be passed to createAndManageUser to
  enable all system apps
- ACTION_MANAGED_USER_CREATED will be broadcasted to ManagedProvisioning
  after managed user is created to take a system app snapshot

Bug: 65842187
Test: OverlayPackagesProviderTest passes
Test: Disallowed system apps does not appear in device owenr, managed
      profile, and managed users
Test: System app snapshot is created after provisinoing device owner,
      managed profile and managed users
Change-Id: I86f870f7814b5700cf5539e889fb6998514d110f