Add workflow that runs the examples about menelaus

[tms-bananaquit]

This is another one that should probably use pip install -e .[test] instead of [dev].

[Anmol-Srivastava]

A Python example-script-runner is added among the unit tests, but the example scripts create a lot of output are not always needed:

• when run by the unit test script, examples should not create output (use test_env_var)
• add unit test script for Jupyter notebooks
• since examples.yml runs only example scripts, unit tests should be reorganized so that the main workflow only runs the non-example test files -- maybe using more directories for labelling, etc.

[Anmol-Srivastava]

Unit tests refactored into tests/menelaus and tests/examples, which also helps the examples.yml and github-ci.yml workflows run those tests separately.

Current issue is FileNotFoundError appearing for multiple instances of example scripts being run by tests/examples/test_example_scripts.py -- even when changing those examples to use os.abspath instead of assuming a root-level CWD.

# in example script
data_path = os.path.join("..", "..", "src", "menelaus", "tools", "artifacts", "example_data.csv")
data_path = os.path.abspath(data_path)
data = pd.read_csv(data_path)

(the failing commit)

[Anmol-Srivastava]

Added unit test script that runs Juypter notebooks. There needed to be some steps to get it working:

• add jupyter, nbconvert to .[test] installation
  - the script assumes there is a kernel made for notebooks in this repository to be run, and that it has a specific name
  • for now, I assume that the user has created a virtual environment at the root level called venv
  • I then do ipython kernell install --name "venv" --user to set that as the kernel for notebooks
  • the unit test script assumes that such a "venv" kernel will always be set up

So, any of those set up steps (and some I may be missing) will need to be included in examples.yml. Apart from that issue, the feature is working as intended, and subsequent commits should pass.