[FLINK-40693][table] Align floating-point IN predicates with equality for signed zero

[ParyshevSergey]

What is the purpose of the change

FLOAT/DOUBLE equality accepts opposite signed zeros, but constant-list IN/NOT IN implemented through SEARCH can reject them because the underlying hash sets use boxed equality. For example, typed runtime rows with IDs [1, 1, 2] and
values [-0.0, -0.0, +0.0] produce [2] for IN (0, 2), while equality produces [1, 1, 2].

This change makes floating-point SEARCH membership consistent with existing numeric equality for signed zero.

Brief change log

• Include both zero representations when preparing a SEARCH constant set containing either zero, after casting to the common type.
• Preserve both representations during code generation.
• Add compiled codegen regressions and SQL integration tests for FLOAT/DOUBLE in batch and streaming.

The general hash-set contracts, generated per-row lookup and NULL handling remain unchanged. Existing NaN behavior is preserved.

Verifying this change

• Verified red → green: 6 assertion failures among 10 new test invocations before the fix; all 10 pass afterward.
• SearchOperatorGenTest covers both zero directions, IN/NOT IN paths, NULL handling, nonzero values, NaN and infinities.
• FloatingPointInITCase verifies runtime raw bits, logical types, generated hash-set code, duplicate rows, singleton and longer lists, and nullable boolean results.
• Targeted unit run: 45 passing invocations across SearchOperatorGenTest, ScalarOperatorsTest, CodeGeneratorContextTest and ConvertToNotInOrInRuleTest.
• Targeted integration run: 46 passing invocations across FloatingPointInITCase and ComparisonFunctionITCase, with JUnit parallel execution disabled for the final run.
• Spotless, Checkstyle, root Apache RAT and git diff --check pass.

Tests used the freshly built runtime artifact. Full CI and release-branch backports were not run.

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): no
• The public API, i.e., is any changed class annotated with @Public(Evolving): no
• The serializers: no
• The runtime per-record code paths (performance sensitive): yes, SEARCH membership results change; implementation changes are confined to preparing the reusable set, with no additional per-record operations or allocations
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: no
• The S3 file system connector: no

Documentation

• Does this pull request introduce a new feature? no
• If yes, how is the feature documented? not applicable
• Release-note draft: FLOAT and DOUBLE constant-list IN/NOT IN now treat opposite signed zeros as equal, consistently with numeric equality.

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Was generative AI tooling used to co-author this PR?

• Yes (please specify the tool below)

Generated-by: Codex (model: GPT-6 Astra; client version not exposed)

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CI report:

• f33614e Azure: SUCCESS

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