Explore using Narwhals in Plotly Express

[LiamConnors]

Narwhals is a compatibility layer between Polars, pandas, and other dataframes.
https://narwhals-dev.github.io/narwhals/

This issue is to explore what changes we would need to make to use Narwhals in Plotly Express.

[firai]

I'm glad that this is being explored! Especially since pandas 3.0 could still add a hard dependency on pyarrow (seems to be their current plan unless the new PDEP delaying the dependency is approved), and since both pyarrow and pandas seem to be required required now for polars to work with Plotly Express.

Not sure if pointing this out here is kosher, and you may already be aware of this, but I understand that this is the (main) PR where altair switched to using narwhals, just for reference: vega/altair#3452. If it's not kosher, feel free to edit this out.