onnxruntime

add google benchmark as direct dependency (#7762)

Co-authored-by: Chen Fu <fuchen@microsoft.com>

Description:
This change add google benchmark git repo as a submodule in onnxruntime repo.

Motivation and Context
Currently we have benchmarking code that depends on google benchmark. The version we are using has cross compilation issues for ARM CPUs. Recent changes in Google benchmark fixed these issues.

Another problem is that we now rely on ONNX to pull in Google benchmark, an indirect dependency. Updating ONNX involves complex steps and rightly so. However, updating Google benchmark dependency should not be hindered by these processes.