HapticGenerator: Add AIDL placeholder implementation and vts test

Bug: 258124419
Test: atest VtsHalHapticGeneratorTargetTest

Change-Id: I576eb32d64412f4eea024d49fd68d3e725483db6
diff --git a/audio/aidl/TEST_MAPPING b/audio/aidl/TEST_MAPPING
index b4607f9..ed2cea2 100644
--- a/audio/aidl/TEST_MAPPING
+++ b/audio/aidl/TEST_MAPPING
@@ -13,6 +13,9 @@
       "name": "VtsHalEqualizerTargetTest"
     },
     {
+      "name": "VtsHalHapticGeneratorTargetTest"
+    },
+    {
       "name": "VtsHalLoudnessEnhancerTargetTest"
     },
     {