Implement Python dataframe interchange protocol

[gdementen]

Pandas 1.5 introduced a new dataframe protocol via the __dataframe__ method.

With some luck, this would make LArray objects work as input with libraries like statsmodels, when those libraries support that (which should happen relatively quickly I suppose).

https://data-apis.org/dataframe-protocol/latest/API.html

[gdementen]

Projects (notably Pandas and Polars) are already moving away from it in favor of the PyCapsule interface. I don't think they will drop support for the protocol soon but they are favouring the PyCapsule interface.