[Python] Distribute typing information

[Stranger6667]

It would be useful if Python artifacts will have type stubs. At the moment, not all editors can utilize docstrings (i.e. some PyCharm versions use them) to get the typing info and it is definitely not enough for a pleasant developer experience.

[messense]

While we don't have auto-generated typing information from pyo3 yet, you can just add a handwritten css_inline.pyi file to bindings/python and maturin will package it automatically.

[Stranger6667]

@messense thanks!