Make powerpolicy internal AIDL stable

- CarService is now a mainline module, so the communication between
CarService and car power policy daemon should be through stable AIDL.

Bug: 190510913
Test: m android.frameworks.automotive.powerpolicy.internal-update-api;
      atest carpowerpolicyserver_test CarPowerManagementServiceUnitTest
      VtsAidlPowerPolicyTargetTest
Change-Id: I31cb706d4c7089ab13a4df902a42b5c50a5978b7
8 files changed