Wrote stubbed out test cases for isGreen function to verify if a commit SHA is promote-able (#78932)
Relates to #76700
**Overview:** Created a test script (`test_print_latest_commits.py`) and wrote stub tests for the future`isGreen` function. I also made a `WorkflowCheck` object to keep track of workflow conclusions in `print_latest_commits.py` which will be useful for implementing`isGreen`.
**Test Plan:** Since `isGreen` has not been implemented yet, only the `test_match_rules` case passes and all others fail. Depending on how we plan to implement isGreen (either using the specifications from #76700 or looking at specific groups of checks in more detail), I will need to make additional test cases.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/78932
Approved by: https://github.com/seemethere
