GH-53519: [Python] Fix StringArray/LargeStringArray.from_buffers to accept int64 arguments

[Asthenia0412]

Background

GH-53519 reports that StringArray.from_buffers() and LargeStringArray.from_buffers() reject valid 64-bit array counters with OverflowError: value too large to convert to int. The issue is that these specialized factory methods declare their length, null_count, and offset parameters as Cython int (32-bit C int), while the underlying Arrow ArrayData counters are int64_t.

In contrast, the generic Array.from_buffers() method accepts unbounded Python integers and passes them through correctly to the C++ layer, which accepts int64_t parameters in MakeWithChildren().

Problem

When users pass valid values above INT32_MAX (2^31) to the specialized StringArray.from_buffers() or LargeStringArray.from_buffers(), Cython throws an OverflowError because the Python integer cannot fit into a 32-bit C int. This unnecessarily limits the API compared to the generic Array.from_buffers().

Solution

Widen the three parameters (length, null_count, offset) from Cython int to int64_t in both StringArray.from_buffers() and LargeStringArray.from_buffers(). This aligns with:

• The underlying C++ ArrayData::MakeWithChildren() signature which uses int64_t
• The generic Array.from_buffers() which already accepts large integers
• Other specialized factories in the same file (e.g., DictionaryArray.from_buffers() already uses int64_t length)

Testing

The change is a straightforward type widening:

• The underlying C++ code already accepts int64_t, so no C++ changes are needed
• No buffer layout changes
• Normal string/binary buffer round-trips continue to work as before
• Values up to INT64_MAX will now be accepted (though practical use is limited by address space)

This fix was verified by code analysis against:\n- The issue's reproduction case\n- The _ensure_compression() patterns\n- Cython declaration conventions used elsewhere in the same file\n\n\nCloses: #53519

• GitHub Issue: [Python] String array buffer factories reject valid 64-bit counters #53519