Add built-in stats rewrite rules

[gatesn]

Summary

• register built-in stats rewrite rules through the session-backed registry
• port comparison, boolean, between, like, list_contains, and cast-aware stat rewrites to StatFn::new_expr(...)
• add aggregate-backed null rewrite rules using all_null and all_non_null
• keep the existing legacy null_count / row_count() rewrite rules so current stored stats continue to work

Tests

• cargo +nightly fmt --all
• cargo test -p vortex-array stats::rewrite::builtins::tests::rewrites_null
• cargo test -p vortex-array stats::rewrite
• cargo clippy --all-targets --all-features

[codspeed-hq]

Merging this PR will improve performance by 12.35%

⚠️ Unknown Walltime execution environment detected

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⚡ 4 improved benchmarks
✅ 1212 untouched benchmarks

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Simulation	encode_varbin[(1000, 2)]	168 µs	148.2 µs	+13.36%
⚡	Simulation	encode_varbin[(1000, 32)]	175 µs	155.4 µs	+12.62%
⚡	Simulation	encode_varbin[(1000, 4)]	168.9 µs	149.4 µs	+13.06%
⚡	Simulation	encode_varbin[(1000, 8)]	165.8 µs	150.2 µs	+10.37%

Tip

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_{Comparing ngates/stats-7707/built-in-rewrite-rules (ad61595) with develop (1f6fb0a)¹}

Footnotes

1. No successful run was found on ngates/stats-7707/min-max-aggregate-fns (aa967fc) during the generation of this report, so develop (1f6fb0a) was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩