Add simple target-side VTS test for IEffectFactory.hal

Bug: 32022706
Change-Id: Id8a5a3ba8d48967beba0ef2e232624ebc185e5c6
Test: build & run test
diff --git a/audio/Android.bp b/audio/Android.bp
index 4117288..3121a36 100644
--- a/audio/Android.bp
+++ b/audio/Android.bp
@@ -3,4 +3,5 @@
     "2.0",
     "common/2.0",
     "effect/2.0",
+    "effect/2.0/vts/functional",
 ]