Introduce a shared class for test utilities. am: 3d0d9ab345 am: 386ae9b0ec

Original change: https://android-review.googlesource.com/c/platform/art/+/2210256

Change-Id: I210c2498daa2262c2b6a60ca65847aea9211a3c4
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>