feat: fix windows decimal casting frame

[comphead]

Which issue does this PR close?

• Closes Windows errors out when RANGE frame is decimal #22113 .

Rationale for this change

RANGE window frames with a DECIMAL ORDER BY column crash at runtime:

SELECT COUNT(*) OVER (
  PARTITION BY 1
  ORDER BY cast(1 as decimal(10, 0)) DESC
  RANGE BETWEEN CURRENT ROW AND 1 FOLLOWING
) FROM (SELECT 1);
-- Internal error: Uncomparable values: Decimal128(Some(0),11,0), Decimal128(Some(1),10,0).

Frame-bound arithmetic (value ± delta) widens the decimal result precision by 1 (Decimal(10,0) ± Decimal(10,0) → Decimal(11,0)). search_in_slice then compares the widened target against the
original ORDER BY column, and ScalarValue::partial_cmp rejects decimals whose precision differs — even when the scale matches and the underlying integer representation is directly comparable.

That precision-equality gate is also inconsistent with SQL semantics: DEC(10,0) 1 and DEC(20,0) 1 represent the same number and should compare equal.

What changes are included in this PR?

datafusion/common/src/scalar/mod.rs

• ScalarValue::partial_cmp for Decimal32 / Decimal64 / Decimal128 / Decimal256: compare underlying values whenever scales match, regardless of declared precision. Different scales still
  return None (rescaling would be required).

datafusion/sqllogictest/test_files/window.slt

• Regression block covering the reporter query verbatim plus ASC/DESC × PRECEDING/FOLLOWING, symmetric N PRECEDING AND N FOLLOWING, and a non-zero-scale DECIMAL(10,2) case over multi-row
  partitions.

[nuno-faria]

Thanks @comphead, LGTM.

[nuno-faria]

I wonder if it would be desirable to also compare decimals of different scales.

[nuno-faria]

nit: reported?