DLC: Expose Setup Parameters and User Preferences as Service.

Accessing these information from a non primary user
needs to go through a service configured with singleUser="true".

Bug: 264272240
Test: atest CtsDeviceLockTestCases
Test: atest DeviceLockControllerRoboTests
Test: atest DeviceLockUnitTests
Test: Verified that prefs.xml and setup-prefs.xml are accessed
only for user 0 DE storage.

Change-Id: I73189fa3e9c4063b0959447fc2ea67205a5f4a7e
16 files changed