[Converter] Multiple pk support; Refactor parquet file to Iceberg data file conversion functions to be Ray distributed tasks.

[Zyiqin-Miranda]

Summary

This PR mainly includes two additions:

1. Adds support for concatenating multiple identifier hash column values to evaluate value equality when enforcing identifier column uniqueness.
2. Refactor parquet file to Iceberg data file conversion to be Ray distributed tasks. Observed that when testing with scale, Pyiceberg function parquet_file_to_iceberg_data_file calls parquet.download_metadata and filesystem._get_file_info() under the hood, which are performance bottlenecks. So refactor the conversion functions to be Ray distributed tasks.

Rationale

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Changes

1. Adding concatenating hash column value logic.
2. Unit tests for multiple identifier value test case.

Impact

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Testing

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If this is a bugfix, explain how the fix has been tested to ensure the bug is resolved without introducing new issues.

Regression Risk

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Checklist

• Unit tests covering the changes have been added

  • If this is a bugfix, regression tests have been added

• E2E testing has been performed

Additional Notes

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[pdames]

LGTM!