Create a skeleton Rust audio control HAL

This is to prove that rust audio control HAL can be built and can
run. The skeleton Rust audio control HAL will return UNKNOWN_ERROR
for all APIs.

Bug: 319474244
Flag: EXEMPT HAL interface change
Test: m android.hardware.automotive.audiocontrol-V4-rust-service

Change-Id: I64916b3eaa8410e0b137b5b34578710899f91324
diff --git a/automotive/audiocontrol/aidl/Android.bp b/automotive/audiocontrol/aidl/Android.bp
index c354069..0eb17fe 100644
--- a/automotive/audiocontrol/aidl/Android.bp
+++ b/automotive/audiocontrol/aidl/Android.bp
@@ -27,6 +27,9 @@
                 "com.android.car.framework",
             ],
         },
+        rust: {
+            enabled: true,
+        },
     },
     versions_with_info: [
         {
@@ -100,3 +103,10 @@
         latest_android_hardware_automotive_audiocontrol + "-java",
     ],
 }
+
+rust_defaults {
+    name: "latest_android_hardware_automotive_audiocontrol_rust",
+    rustlibs: [
+        latest_android_hardware_automotive_audiocontrol + "-rust",
+    ],
+}