fix: reject inconsistent parameterized ScalarValues

[Theodus]

Which issue does this PR close?

• Closes ScalarValue::iter_to_array accepts mismatched type parameters #24538.

Rationale for this change

The ScalarValue conversion fuzz tests round-trip arrays whose scalars all have the same DataType. The generator also omits timestamps with timezones and FixedSizeBinary arrays. The tests therefore do not cover mismatched type parameters.

The added coverage exposes a bug in ScalarValue::iter_to_array. The function accepts mismatched decimal precision, decimal scale, timestamp timezone, and fixed-size binary width. It builds the array with the first scalar's parameters and discards the conflicting parameters.

What changes are included in this PR?

• Generate timestamps with timezones and FixedSizeBinary arrays with widths 1, 8, and 32.
• Mutate each parameter independently and verify that ScalarValue::iter_to_array rejects the mismatch.
• Make ScalarValue::iter_to_array reject inconsistent decimal parameters, timestamp timezones, and fixed-size binary widths.
• Reuse index and null generation across the binary array generators.

Are these changes tested?

Yes. scalar_value_iter_to_array_rejects_mixed_parameterized_types covers decimal precision, decimal scale, timestamp timezone, and fixed-size binary width mismatches. The existing roundtrip test now covers timestamps with timezones and FixedSizeBinary arrays.

Are there any user-facing changes?

Yes. ScalarValue::iter_to_array now returns an error when its inputs have different parameterized logical types. The public API signature does not change.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 32.55814% with 29 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.32%. Comparing base (8332cfa) to head (a797e0c).

Files with missing lines	Patch %	Lines
test-utils/src/array_gen/binary.rs	0.00%	16 Missing ⚠️
datafusion/common/src/scalar/mod.rs	51.85%	13 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #24539      +/-   ##
==========================================
- Coverage   81.32%   81.32%   -0.01%     
==========================================
  Files        1117     1117              
  Lines      396269   396280      +11     
  Branches   396269   396280      +11     
==========================================
- Hits       322260   322255       -5     
- Misses      55186    55197      +11     
- Partials    18823    18828       +5     

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