Python: pyodide strategy

[kylebarron]

I think it's an important differentiator for geoarrow-rust to work in pyodide. The biggest blocker here is that multiple-pymethods doesn't work for the wasm32-unknown-emscripten target (see PyO3/pyo3#2517 and PyO3/pyo3#3628).

• Conditionally compile only top-level functions and data classes with only core methods.
• dev docs for compiling to pyodide
• Add note to class methods that those don't exist in the pyodide build.
• Add CI testing to verify that the --no-default-features build works when compiling to emscripten
• Future work: connect to documentation, e.g. with https://github.com/samuelcolvin/mkdocs-run-code

[kylebarron]

ref: https://pyodide.org/en/stable/development/building-and-testing-packages.html, https://blog.pyodide.org/posts/rust-pyo3-support-in-pyodide/, pola-rs/polars#3672 (comment)

[kylebarron]

To simplify development overhead and maintenance, we're moving to only top-level functions anyways, so hopefully pyodide should be on the roadmap

[kylebarron]

Closed with #753