Visualizer: Add AIDL placeholder implementation and vts test cases

Bug: 258124419
Test: atest VtsHalVisualizerTargetTest

Change-Id: I8bfdb234d1ac3f57b12096d3f02dd1bad92b1d0f
diff --git a/audio/aidl/vts/Android.bp b/audio/aidl/vts/Android.bp
index 068742d..4414e26 100644
--- a/audio/aidl/vts/Android.bp
+++ b/audio/aidl/vts/Android.bp
@@ -83,3 +83,9 @@
     defaults: ["VtsHalAudioTargetTestDefaults"],
     srcs: ["VtsHalLoudnessEnhancerTargetTest.cpp"],
 }
+
+cc_test {
+    name: "VtsHalVisualizerTargetTest",
+    defaults: ["VtsHalAudioTargetTestDefaults"],
+    srcs: ["VtsHalVisualizerTargetTest.cpp"],
+}