feat: Raw api polars integration

[christoffer-hk]

Description

Started on an integration with Polars, as an alternative to Pandas. Beginning with RAW rows (RowCore and RowListCore) and a retrieve_polars_dataframe function in the RawRowsAPI. Currently implemented the bare minimum to have mostly feature parity with how we integrate with Pandas.

This only scratches the surface with what is technically possible to do with Polars. I believe there is a lot of potential in using Polars, especially now in version 8> with running things async. A lot of cool topics are mentioned here in a comparison written by Polars https://docs.pola.rs/user-guide/migration/pandas/ .

Checklist:

• Tests added/updated.
• Documentation updated. Documentation is generated from docstrings - these must be updated according to your change.
  If a new method has been added it should be referenced in cognite.rst in order to generate docs based on its docstring.
• The PR title follows the Conventional Commit spec.

[gemini-code-assist]

Code Review

This pull request adds Polars DataFrame support to the raw rows API and data classes. The review feedback highlights several instances where unpacking row columns could raise a TypeError if the columns are None, suggesting defensive unpacking with **(columns or {}).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.65%. Comparing base (5309e35) to head (77744ac).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2678      +/-   ##
==========================================
- Coverage   93.65%   93.65%   -0.01%     
==========================================
  Files         498      498              
  Lines       50342    50460     +118     
==========================================
+ Hits        47148    47258     +110     
- Misses       3194     3202       +8     

Files with missing lines	Coverage Δ
cognite/client/_api/raw/rows.py	91.37% <100.00%> (+0.36%)	⬆️
cognite/client/_sync_api/raw/rows.py	100.00% <100.00%> (ø)
cognite/client/data_classes/_base.py	93.79% <100.00%> (+0.01%)	⬆️
cognite/client/data_classes/raw.py	96.47% <100.00%> (+0.23%)	⬆️
tests/tests_unit/test_api/test_raw.py	100.00% <100.00%> (ø)

... and 6 files with indirect coverage changes

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[christoffer-hk]

A couple comments from myself.

• The sync-client-codegen does not add the polars import properly into the _sync_api; it falls outside of the TYPE_CHECKING check.
• I have not ensured symmetry on purpose, by not making an implementation for something like insert_polars_dataframe to keep the size of the PR low.
• I have to use the runtime compatibility version of polars (rtcompat) due to running under rosetta. While gemini suggests it should be ok for other devs to work with that, it'd be nice if someone could verify. Otherwise I suppose we need a different dev-dependency group to handle the different versions of polars.