Audio AIDL : Add placeholder implementation and VTS test case for AGC1

Bug: 258124419
Test: atest VtsHalAGC1TargetTest
Change-Id: Ia9894ac21b284a554f8c2d66966d07e5e4621ccd
diff --git a/audio/aidl/TEST_MAPPING b/audio/aidl/TEST_MAPPING
index f030af0f..3e06595 100644
--- a/audio/aidl/TEST_MAPPING
+++ b/audio/aidl/TEST_MAPPING
@@ -40,6 +40,9 @@
       "name": "VtsHalAECTargetTest"
     },
     {
+      "name": "VtsHalAGC1TargetTest"
+    },
+    {
       "name": "VtsHalAGC2TargetTest"
     },
     {