fix: array_min/array_max on zero rows for non-primitive element types

[linuxpi]

Which issue does this PR close?

• Closes array_min / array_max fail on a zero-row batch for non-primitive element types #26072.

Rationale for this change

On a zero-row List<Utf8> (or other non-primitive element type), array_min / array_max fail with Empty iterator passed to ScalarValue::iter_to_array. ProjectionExec and TopK evaluate expressions on empty batches, so the query fails instead of returning no rows.

What changes are included in this PR?

• array_min_max_helper returns new_empty_array(&array.value_type()) for an empty input before the ScalarValue fallback. The primitive fast path is unchanged.
• First unit tests for min_max.rs: zero-row List/LargeList<Utf8>, zero-row List<Int64>, mixed rows, and invoke_with_args with number_rows: 0.

Are these changes tested?

Yes. Without the fix, the zero-row Utf8 tests fail with the error above.

Are there any user-facing changes?

No.