perf: DH-22420: Skip Unnecessary Single Value Columns when Sorting

[cpwright]

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[github-actions]

No docs changes detected for 262afb0

[Copilot]

Pull request overview

This PR implements a sorting optimization in the Deephaven engine to avoid doing sort work for sort keys that cannot affect ordering (single-value / row-key-agnostic columns), including a no-op “identity” mapping when all sort keys are constant.

Changes:

• Add logic in SortHelpers.getSortedKeys to drop row-key-agnostic sort columns (when the comparator respects equality) and return an identity mapping when all keys are constant.
• Refactor row-redirection utilities by extracting StaticWrappedRowSetRowRedirection and reusing it from WrappedRowSetRowRedirection.
• Add test coverage to validate behavior for constant, null-value, and non-equality-respecting comparator cases.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
engine/table/src/test/java/io/deephaven/engine/table/impl/MultiColumnSortTest.java	Adds tests for skipping constant / null sort columns and identity-sort behavior.
engine/table/src/main/java/io/deephaven/engine/table/impl/util/WrappedRowSetRowRedirection.java	Refactors to extend StaticWrappedRowSetRowRedirection and updates prev-chunk behavior.
engine/table/src/main/java/io/deephaven/engine/table/impl/util/StaticWrappedRowSetRowRedirection.java	New reusable base implementation for wrapped-RowSet redirection.
engine/table/src/main/java/io/deephaven/engine/table/impl/SortOperation.java	Treats identity mapping as already-sorted and generalizes historical redirection type.
engine/table/src/main/java/io/deephaven/engine/table/impl/SortHelpers.java	Implements constant-column skipping and introduces IdentitySortMapping.

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[lbooker42]

This looks good and is rather clever.