Clean up Readback test

Readback will be used in RenderEngine testing.  Clean up test files and
extract common classes

Bug: 133411821
Test: build, boot, VtsHalGraphicsComposerV2_2TargetTest
Change-Id: I45b4666348ae0137dd2a7825b5cfd627a1e1aa58
diff --git a/graphics/composer/2.2/utils/vts/Android.bp b/graphics/composer/2.2/utils/vts/Android.bp
index c6b524d..4016120 100644
--- a/graphics/composer/2.2/utils/vts/Android.bp
+++ b/graphics/composer/2.2/utils/vts/Android.bp
@@ -19,12 +19,15 @@
     defaults: ["hidl_defaults"],
     srcs: [
         "ComposerVts.cpp",
+        "ReadbackVts.cpp",
     ],
     static_libs: [
         "VtsHalHidlTargetTestBase",
         "android.hardware.graphics.composer@2.1",
         "android.hardware.graphics.composer@2.1-vts",
         "android.hardware.graphics.composer@2.2",
+        "android.hardware.graphics.mapper@2.1",
+        "android.hardware.graphics.mapper@2.1-vts",
     ],
     export_static_lib_headers: [
         "android.hardware.graphics.composer@2.1-vts",