Extend set user protected packages for multi-user

The current implementation does not work when the multi-user feature is
enabled because it clears the "globally" protected packages set by the
device owner whenever a new user is created.

Bug: 178500150
Test: atest FrameworksServicesTests:com.android.server.devicepolicy.OwnersTest
Test: atest FrameworksServicesTests:com.android.server.devicepolicy.DevicePolicyManagerTest
Test: Ran the CTS tests that were added

Change-Id: Id04cb9b5b2357b0a0b5090442a39d97405287dbe