Modified DPM KEYGUARD_DISABLE_SECURE_NOTIFICATIONS restriction

* Introduced logic that allows the profile owner of an
  organization-owned device (COPE PO) to set the restriction
  KEYGUARD_DISABLE_SECURE_NOTIFICATIONS on the parent profile.

Bug: 149007069
Test: Manual testing with TestDPC
      atest com.android.cts.devicepolicy.OrgOwnedProfileOwnerTest#testSetKeyguardDisabledFeatures
      atest com.android.cts.devicepolicy.MixedDeviceOwnerTest#testSetKeyguardDisabledFeatures
      atest com.android.cts.devicepolicy.MixedManagedProfileOwnerTest#testSetKeyguardDisabledFeatures
      atest com.android.cts.devicepolicy.MixedDeviceOwnerTest#testSetKeyguardDisabledFeaturesLogged

Change-Id: I06d8985471bdae3386ba68d67467f136668a4ca4