ENH: Adding support for Polars

[dengemann]

Polars is written in Rust (fast + lazy eval) and looks like an interesting option to consider when it comes to scaling up our object DataFrames.

https://pola-rs.github.io/polars-book/user-guide/introduction.html

Opening this issues to bookmark the idea for later.

[dengemann]

inconclusive – unclear if we have a real bottleneck at this point.