fixing factorial negative values

[raushanprabhakar1]

Which issue does this PR close?

• Closes PostgreSQL compatibility: factorial of a negative value should error #22270

Rationale for this change

PostgreSQL returns a domain error for factorial on negative inputs (ERROR: factorial of a negative number is undefined). DataFusion incorrectly returned 1 for negative values (e.g. factorial(-1)), which breaks PostgreSQL-aligned SQL semantics and can silently produce wrong results.

What changes are included in this PR?

• factorial (core / datafusion-functions): Negative arguments now fail with an execution error and message aligned with PostgreSQL: factorial of a negative number is undefined, instead of returning 1.
• Documentation: Updated the #[user_doc] description so it matches behavior (non-negative inputs; error on negative values and on overflow).
• Tests: Added a sqllogictest in math.slt that expects this error for factorial(-1).

Note: Spark’s factorial in datafusion-spark is unchanged (PySpark-style nulls for out-of-domain values).

Are these changes tested?

Yes. A sqllogictest was added in datafusion/sqllogictest/test_files/math.slt for SELECT factorial(-1).

Are there any user-facing changes?

Yes. factorial with a negative argument now errors at execution time instead of returning 1. This matches PostgreSQL and fixes incorrect results; callers that relied on the old behavior would need to adjust.

No public Rust API breakage in exported types; behavior change is SQL/UDF semantics for negative inputs.

[raushanprabhakar1]

Hi @Dandandan , requesting you to review. Thanks.