GH-3406: fix Float16 statistics handling for NaN and zero values

[HuaHuaY]

Rationale for this change

1. When creating column index and NaN is the min or max value, column index will not be generated.
2. When creating statistic and the min value is +0, the min value will be changed to -0. When the max value is -0, it will be changed to +0.

What changes are included in this PR?

• In Statistics<>.Float16Builder and BinaryColumnIndexBuilder, this PR will adjust value when the min or max value is +0 or -0.
• In BinaryColumnIndexBuilder, this PR will mark the column index is invalid when the min or max value is NaN.
• In Statistics<>.Float16Builder, statistic will be changed to (+0.0, +0.0) which is the same behavior as Double.

Are these changes tested?

Yes.

Are there any user-facing changes?

Yes. This PR corrects the behavior about Float16.

Closes#3406

[Copilot]

Pull request overview

Fixes Float16 min/max edge cases so statistics and column indexes behave correctly when encountering NaN and signed-zero values, aligning behavior with Float/Double semantics and preventing invalid column indexes from being produced.

Changes:

• Add shared Float16Binary constants for +0/-0 and reuse them in statistics/index logic.
• Normalize Float16 min/max for signed zero and invalidate Float16 column indexes when NaN is present.
• Update/extend Hadoop round-trip tests to cover signed-zero normalization and NaN column-index invalidation.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
parquet-hadoop/src/test/java/org/apache/parquet/statistics/TestFloat16Statistics.java	Updates expected min/max placeholders for NaN stats handling.
parquet-hadoop/src/test/java/org/apache/parquet/statistics/TestFloat16ReadWriteRoundTrip.java	Adjusts zero-related expectations and adds a NaN column-index test expecting no index.
parquet-column/src/main/java/org/apache/parquet/schema/Float16.java	Introduces shared +0/-0 Float16 Binary constants.
parquet-column/src/main/java/org/apache/parquet/internal/column/columnindex/BinaryColumnIndexBuilder.java	Adds Float16-specific normalization (+0/-0) and NaN invalidation for column index creation.
parquet-column/src/main/java/org/apache/parquet/column/statistics/Statistics.java	Reuses Float16 constants and aligns NaN placeholder behavior with float/double builders.

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[HuaHuaY]

Please take a look again @wgtmac

[wgtmac]

@gszadovszky Could you help review this as well? I think this fix makes a lot of sense to be consistent with what currently float and double types do.

[wgtmac]

Thanks @HuaHuaY for fixing this and @gszadovszky for the review!