FIX: Support Arrow View types in bulk copy

[gargsaumya]

Work Item / Issue Reference

GitHub Issue: #708
ADO: AB#47279

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Summary

Adds an end-to-end regression test for passing a Polars DataFrame with an Arrow string_view column directly to Cursor.bulkcopy_arrow. The test asserts the exported Arrow type and verifies values and NULLs round-trip through SQL Server without calling DataFrame.to_arrow().

Adds Polars to the test requirements so the regression runs in CI instead of being skipped.

Depends on microsoft/mssql-rs#259 and publication of the fixed mssql_py_core 0.1.9 wheel. After publication, this branch must update eng/versions/mssql-py-core.version from 0.1.8 to 0.1.9 before it is ready to merge.

Validation

• Live SQL Server: TestBulkcopyArrowLive::test_polars_string_view_c_stream passed
• Black check passed for tests/test_024_bulkcopy_arrow.py
• git diff --check passed