Some initial changes to introduce Pytest into the code

[rohin-dasari]

• updated all existing tests to use pytest
• updated github action
• organized util test files in separate folder
• started using logging.info instead of print

[aadharna]

Since we're moving to pytest, we should implement something like the `init ray before all tests and then tear it down' stuff mentioned in #20 so we then add in the full ray integration into the tests so that can properly test more of the pieces of the code.