fix(spark): correct mod ANSI zero divisor and negative zero handling

[u70b3]

Which issue does this PR close?

• Closes [Bug] mod returns NaN instead of raising for a zero floating point divisor in ANSI mode, and ignores -0.0 divisors #23894

Rationale for this change

datafusion-spark's mod routes through the shared try_rem helper in
datafusion/spark/src/function/math/modulus.rs, which has two gaps in its
zero-divisor handling (both verified against Spark 3.5.8 – 4.2.0 in the issue):

1. ANSI mode, floating-point divisor. try_rem delegates to Arrow's rem
   kernel in ANSI mode, but Arrow only reports division by zero for integer and
   decimal types. Floating-point divisors follow IEEE 754 and quietly produce
   NaN, while Spark raises REMAINDER_BY_ZERO for a zero divisor of any
   numeric type:

   set datafusion.execution.enable_ansi_mode = true;
   SELECT mod(10.5::float8, 0.0::float8);  -- NaN, Spark raises

2. -0.0 divisor, both modes. The legacy path nulls out zero divisors via
   eq(right, 0), but Arrow's floating-point comparisons use a total order in
   which -0.0 is distinct from 0.0, so a -0.0 divisor goes unrecognised.
   Spark's isZero is a numeric comparison and treats -0.0 as zero:

   SELECT mod(10.5::float8, -0.0::float8);  -- NaN, Spark returns NULL (legacy)

What changes are included in this PR?

try_rem now detects zero divisors itself, mirroring the shape #23898
established for pmod:

• A new is_zero helper counts -0.0 as zero for the floating-point types
  (via a negative_zero companion, same as fix(spark): correct pmod overflow, ANSI zero divisor and negative zero handling #23898).
• In ANSI mode, any row with a zero divisor raises ArrowError::DivideByZero
  — the same error Arrow's rem already produces for integers today, so the
  message stays uniform across types. The check is masked by the validity of
  the dividend because Spark's remainder expressions are null intolerant: a
  NULL dividend short-circuits to NULL before the divisor is validated, so
  mod(NULL, 0) must return NULL rather than raise.
• Both modes substitute NULL for zero divisors before calling Arrow's rem,
  so the kernel never sees a zero divisor: legacy mode gets NULLs, and ANSI
  mode has already raised on the rows that required it.

Note on overlap with #23898: that PR rewrites pmod to no longer use
try_rem and adds identical is_zero/negative_zero helpers. This PR is
independent of it — mod is fixed either way — but whichever lands second
should dedupe the helpers in a rebase. Until #23898 lands, pmod also picks
up the -0.0 and ANSI floating-point zero-divisor fixes through the shared
helper.

Out of scope: #23897 (reproducing Spark's exact ANSI error text) is a
repository-wide error-message policy question, as noted in that issue.

Are these changes tested?

Yes:

• New unit tests in modulus.rs: ANSI floating-point zero divisor raises;
  -0.0 divisor returns NULL in legacy mode and raises in ANSI mode; a NULL
  dividend with a zero divisor returns NULL in ANSI mode (integer and float).
• New sqllogictest cases in spark/math/mod.slt covering the same behavior at
  SQL level.
• Verified cargo test -p datafusion-spark, the spark/math/mod.slt and
  spark/math/pmod.slt sqllogictests, ./dev/rust_lint.sh, and the extended
  workspace suite (ci profile with
  avro,json,backtrace,extended_tests,recursive_protection,parquet_encryption)
  — all green.

Are there any user-facing changes?

Only the bug fixes, and only for the Spark mod/pmod functions: in ANSI
mode a floating-point zero divisor now raises instead of returning NaN, and a
-0.0 divisor is treated as zero in both modes (NULL in legacy mode, an error
in ANSI mode), matching Spark. No API changes.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 83.95062% with 13 lines in your changes missing coverage. Please review.
✅ Project coverage is 80.87%. Comparing base (62650ef) to head (f3c194b).

Files with missing lines	Patch %	Lines
datafusion/spark/src/function/math/modulus.rs	83.95%	3 Missing and 10 partials ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #23987   +/-   ##
=======================================
  Coverage   80.87%   80.87%           
=======================================
  Files        1101     1101           
  Lines      375765   375837   +72     
  Branches   375765   375837   +72     
=======================================
+ Hits       303915   303974   +59     
- Misses      53747    53751    +4     
- Partials    18103    18112    +9     

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[kumarUjjawal]

Hi @u70b3 Thank you for working on this. I believe there's already a PR for this here #23898

[u70b3]

Thanks for checking, @kumarUjjawal. There is some implementation overlap, but the two PRs fix different functions.

#23898 is scoped to pmod: it rewrites spark_pmod so that it no longer uses try_rem, while leaving mod behavior unchanged. This PR fixes mod by correcting try_rem and adds coverage in mod.slt, closing #23894.

The shared overlap is the negative_zero/is_zero helpers. I will rebase and deduplicate those helpers after whichever PR lands first.