Automatic stub file generation

[g-bauer]

Work in progress of automatic stub file generation using experimental-inspect and pyo3-introspection. See the documentation and the related issue.

Currently missing

• Proper support for enum variants. Currently doesn't show variants for autocompletion.
• Docstrings are currently not added to stubs. They seem to work in jupyter and marimo due to dynamically loading the docstrings.
• SIObject (PyObjects defined in other crates) - can be managed via custom signature
• Return types - can be managed via custom signature as well.

How to use this

Inside feos/py-feos:

1. Generate cdylib via maturin
2. Run cargo run --bin stub_gen. You might need to adjust the path. We could add a command line argument for this.
3. The above command generates feos.pyi.
4. Run maturin again. It will now include the stub file. (Look for 📖 Found type stub file at feos.pyi)

GH Action

• Add stub generation step for wheel-test action. Load stub file in publishing action.
• In the future, this might be a feature of maturin

Todo

• Check if stubs can be used with mkdocs