Add data source sinks for Polars LazyFrame (#791)

[Chowdhury-Anik]

This commit adds four data sink methods for Polars LazyFrame:

• sink_parquet: Write LazyFrame to Parquet format
• sink_csv: Write LazyFrame to CSV format
• sink_ipc: Write LazyFrame to IPC/Feather format
• sink_ndjson: Write LazyFrame to NDJSON format

These sinks allow users to write LazyFrames directly without needing to call .collect() first, improving performance for large datasets.

Fixes #791

Changes

How I tested this

Notes

Checklist

• PR has an informative and human-readable title (this will be pulled into the release notes)
• Changes are limited to a single goal (no scope creep)
• Code passed the pre-commit check & code is left cleaner/nicer than when first encountered.
• Any change in functionality is tested
• New functions are documented (with a description, list of inputs, and expected output)
• Placeholder code is flagged / future TODOs are captured in comments
• Project documentation has been updated if adding/changing functionality.

[elijahbenizzy]

Looks good -- maybe add a test?

[skrawcz]

Just need some tests please