Expose MANAGED_PROVISIONING_DPC_DOWNLOADED via DevicePolicyManager

Expose Settings.Secure.MANAGED_PROVISIONING_DPC_DOWNLOADED by adding
getter & setter methods in DevicePolicyManager.

Bug: 212679631

Test: android.devicepolicy.cts.DevicePolicyManagerTest
Change-Id: I9c8c69ec494fcbf82965308b76f6e27e5184ba4d
4 files changed