refactor: Make CollectLeftAccumulator a trait for custom left-side accumulators

[peasee]

• Updates CollectLeftAccumulator struct to MinMaxLeftAccumulator
• Creates the CollectLeftAccumulator and implements it for MinMaxLeftAccumulator
• Updates HashJoinExec::try_new to set a default accumulator for MinMaxLeftAccumulator. This ensures the refactor is not a breaking change by defaulting the generic type.
• Updates ColumnBounds to MinMaxColumnBounds
• Creates the ColumnBounds trait which returns Arc<dyn PhysicalExpr> representing the expression for the bounds returned by the accumulator. Implements it for MinMaxColumnBounds

This refactor maintains existing min-max bounds functionality, while providing the ability for consumers to override HashJoinExec's with custom accumulators for their specific use case.

• Makes some structs and methods from pruning public, to make it easier to build custom pruners.

[peasee]

Physical planner tests - failure is unrelated to changes, and due to feature flagging:

---- spill::tests::test_spill_compression stdout ----

thread 'spill::tests::test_spill_compression' panicked at /home/owner/.cargo/git/checkouts/arrow-rs-ddec0d7286d46bb5/a55ba62/arrow-ipc/src/writer.rs:1134:14:
StreamWriter is configured to not error on dictionary replacement: InvalidArgumentError("zstd IPC compression requires the zstd feature")


failures:
    spill::tests::test_spill_compression

test result: FAILED. 920 passed; 1 failed; 0 ignored; 0 measured; 0 filtered out; finished in 9.08s

[Copilot]

Pull request overview

This PR refactors the hash join bounds accumulation system to support custom accumulator implementations through traits. The refactor maintains backward compatibility by providing a default MinMaxLeftAccumulator implementation while enabling consumers to implement custom accumulator logic.

Key changes:

• Introduces CollectLeftAccumulator and ColumnBounds traits for extensibility
• Renames CollectLeftAccumulator struct to MinMaxLeftAccumulator and ColumnBounds struct to MinMaxColumnBounds
• Makes HashJoinExec generic over the accumulator type with MinMaxLeftAccumulator as the default
• Exposes previously internal types and functions through public APIs to support custom implementations

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
datafusion/pruning/src/pruning_predicate.rs	Exposes internal utilities (BoolVecBuilder, build_statistics_record_batch, StatisticsType) as public APIs
datafusion/pruning/src/lib.rs	Re-exports newly public types from pruning_predicate module
datafusion/physical-plan/src/joins/mod.rs	Re-exports new trait types and renamed accumulator from hash_join module
datafusion/physical-plan/src/joins/hash_join/shared_bounds.rs	Introduces ColumnBounds trait, renames ColumnBounds struct to MinMaxColumnBounds, updates types to use trait objects
datafusion/physical-plan/src/joins/hash_join/mod.rs	Re-exports new public types (CollectLeftAccumulator, MinMaxLeftAccumulator, ColumnBounds)
datafusion/physical-plan/src/joins/hash_join/exec.rs	Makes HashJoinExec generic over accumulator type, introduces CollectLeftAccumulator trait, renames struct to MinMaxLeftAccumulator, adds try_new_with_accumulator method

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