feat(python): Improve ipython autocomplete for LazyFrame and DataFrame

[ritchie46]

Can again confirm that this ensures autocomplete remains working in notebooks.

[codecov]

Codecov Report

Attention: Patch coverage is 97.77778% with 1 line in your changes missing coverage. Please review.

Project coverage is 80.85%. Comparing base (88cfb23) to head (08d9ce6).

❗ Current head 08d9ce6 differs from pull request most recent head e9ba7b6

Please upload reports for the commit e9ba7b6 to get more accurate results.

Files	Patch %	Lines
py-polars/polars/lazyframe/frame.py	94.73%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #17091      +/-   ##
==========================================
- Coverage   80.88%   80.85%   -0.03%     
==========================================
  Files        1456     1456              
  Lines      191155   191155              
  Branches     2731     2731              
==========================================
- Hits       154611   154562      -49     
- Misses      36038    36087      +49     
  Partials      506      506              

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[borchero]

I just noticed that this also resolves #14741 (albeit for a different purpose 😄) ... thanks! 😁