EnvironmentalReverb: Add AIDL placeholder implementation and its unit test

Bug: 258124419
Test: atest VtsHalEnvironmentalReverbTargetTest

Change-Id: I8e8b569a493e6d9c36e2023fdbe6657a7732ed72
diff --git a/audio/aidl/TEST_MAPPING b/audio/aidl/TEST_MAPPING
index cafbf59..bf86d01 100644
--- a/audio/aidl/TEST_MAPPING
+++ b/audio/aidl/TEST_MAPPING
@@ -13,6 +13,9 @@
       "name": "VtsHalDownmixTargetTest"
     },
     {
+      "name": "VtsHalEnvironmentalReverbTargetTest"
+    },
+    {
       "name": "VtsHalEqualizerTargetTest"
     },
     {