Add git handling in run_sys_tests to git_utils.py module

@negin513 introduced a new module git_utils.py. There is currently a private subroutine in run_sys_tests.py _record_git_status that I wonder if it shouldn't be added to git_utils.py. Right now run_sys_tests.py is the only python code that does this git status type check. But, I wonder if it might be useful for other python code or future code? Even if run_sys_tests.py is the only one that uses it, it's still nice to have all the git python interaction in one place. There might be instances when all the git code needs to be updated, and it would be best if it were all in one place.

Does anyone have thoughts on this idea? Is it worth doing?