graphics: add basic target-side tests for IComposer

Add graphics_composer_hidl_hal_test.

Test: manual execution
Change-Id: I38c2fcd5cfb27dcd0299df389cbf84fe4056de1b
diff --git a/graphics/Android.bp b/graphics/Android.bp
index 6d55dd1..eaa47ae 100644
--- a/graphics/Android.bp
+++ b/graphics/Android.bp
@@ -6,6 +6,7 @@
     "common/1.0",
     "composer/2.1",
     "composer/2.1/default",
+    "composer/2.1/vts/functional",
     "mapper/2.0",
     "mapper/2.0/default",
     "mapper/2.0/vts/functional",