Add factory reset protection policy Test API to DPM

* Add @TestApi isFactoryResetProtectionPolicySupported()
  to DevicePolicyManager which returns whether factory
  reset protection policy is supported on the device.

Bug: 153696811
Test: atest com.android.cts.devicepolicy.OrgOwnedProfileOwnerTest#testFactoryResetProtectionPolicy
Change-Id: Id0bd6cdacf33f0fb2f795e1ead5127b79f42960e