Review / improve the logic for skipping tests

[gpsaggese]

Right now the logic for running tests specific of a repo / machine is pretty messy.

We want to:

• [ ] Explain how it works right now (in the internal doc and maybe a note in the white paper)
• [ ] Decide how it should work (updating the docs)
• [ ] Clean up the code

Let's have @heanhsok @samarth9008 (and @sonniki) keep an eye on it

[Shaunak01]

We have some documentation at: - https://github.com/causify-ai/helpers/blob/master/docs/coding/all.run_unit_tests.how_to_guide.md#running-tests-on-gh-actions - And we can skip tests on submodule using invoke

@gpsaggese What is our goal here? - Do we want the logic to skip specific tests in a PR? - For which we either comment out the code or skip using pytest.

[gpsaggese]

Let's pause this one as low priority.