Add getLocationFlags getter to PackageManagerNative.

This information is required for enforcing NNAPI Vendor Extensions
restrictions in libneuralnetworks.so library.

What it does is already possible using ApplicationInfo, but in native code
there's no equivalent to platform private (non-exposed public), because of
that I had to create getLocationFlags as an explicit API.

Bug: 120483623
Test: CtsNNAPITestCases

Change-Id: I0b3a5a4f3559b2d1d44088c8fa1d5bb5605c83cb
Merged-In: I0b3a5a4f3559b2d1d44088c8fa1d5bb5605c83cb
(cherry picked from commit a4a631ea)