Creates com.android.car.audio package

Foresee there will be more audio specific classes, and it's better
having them in a dedicated package.

CarAudioService is moved to audio package as well. Comments are added to
the public classes / interfaces to comply with the lint check (and it's
a good practice doing so).

Bug: 113051081
Test: m -j
Change-Id: I1fa9886f651f253f1a285d0f50be504808acd6e4
diff --git a/service/src/com/android/car/ICarImpl.java b/service/src/com/android/car/ICarImpl.java
index 2081148..736ffc8 100644
--- a/service/src/com/android/car/ICarImpl.java
+++ b/service/src/com/android/car/ICarImpl.java
@@ -35,6 +35,7 @@
 import android.util.Slog;
 import android.util.TimingsTraceLog;
 
+import com.android.car.audio.CarAudioService;
 import com.android.car.cluster.InstrumentClusterService;
 import com.android.car.garagemode.GarageModeService;
 import com.android.car.hal.VehicleHal;