audio: Implement VTS tests for V7.0

The major change in V7.0 is use of enum values defined
in the Audio Policy Configuration XSD schema. This allows
decoupling types used at the HIDL layer from system/audio.h.
Added a header audio_policy_configuration_V7_0-enums.h
with utility functions analogous to ones from system/audio.h
but defined for the types generated from XSD schema.

Since the code of VTS tests is shared between versions,
ensured that the VTS tests for the previous HAL versions
didn't regress.

Bug: 142480271
Test: atest VtsHalAudioV6_0TargetTest
      atest VtsHalAudioEffectV6_0TargetTest
      atest VtsHalAudioV7_0TargetTest
      atest VtsHalAudioEffectV7_0TargetTest
Change-Id: Ia7c2d49a02783725080c8fed6a25853e91bba487