Extending Memory Tagging test to cover DPM

When the Memory Tagging Extension is turned on by Android's Advanced
Protection Mode, this should be reflected in the value returned by
the DevicePolicyManager's getMtePolicy method.

To call this method, the test needs an additional permission - MANAGE_DEVICE_POLICY_MTE

Bug: 402456665
Test: atest CtsSecurityTestCases:android.security.cts.advancedprotection.MemoryTaggingExtensionTest
Flag: EXEMPT bugfix

Change-Id: I37d71c4c5269dbc648589a69a539dd044dfe002a