Add a native aidl API.

Introduce a platform_compat_native service that just calls the
platform_compat service.
The new service is needed as it needs a slightly different (more
limited, no ApplicationInfo in cpp) aidl API, and a class can only
extend one stub.

Test: Call the service from dumpsys.cpp (http://aosp/1142055)
Bug: 138275545
Change-Id: Ic46cc34b4c1dd4ebc6bcc996fb3f8503607214ac
Merged-In: Ic46cc34b4c1dd4ebc6bcc996fb3f8503607214ac