* Create gtest submodule and point benchmark to master
* Added submodule files for gtest
* Update benchmark submodule
* Add googletest to top level cmake so that any gtest_adds are not dependent on benchmark.
* Update buildbot, circle CI and travis CI
* Copy test-onnx-mlir.sh to docker container
* build dependencies for tests
Co-authored-by: Tian Jin <tjingrant@gmail.com>
NathanielMcVicar