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

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

Change-Id: I2feaf433f7d4e7964d4aaa8b2dea352e5a16c3b5
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>