Add Polars plugin

[areleu]

Overview

Hi guys, I was wondering if you are working on supporting polars: https://pola.rs/

If not I have been working on a plugin here: https://github.com/areleu/frictionless-py/tree/polars-plugin

It is still missing some tests and I have to sort out some edge cases but let me know if you are interested on including this feature. I would find it very valuable because as of the last couple of months I have been working almost exclusively with polars and not pandas.

By the way, I have been inspiring a lot from the pandas plugin so some things may look similar, my initial approach was only copying the files and working through the error messages.