perf(arrow/array): skip full-range SliceEqual slices

[fallintoplace]

Summary

• Skip temporary arrays when both ranges cover their full inputs.
• Keep the existing NewSlice path for partial ranges.
• This also helps ChunkedEqual when chunk boundaries line up.
• Add full-range semantic coverage and benchmarks.

Benchmark

Local Apple M1 Pro. -benchtime=500ms -count=3.

Case	main	change
SliceEqual int64, 64 values	~700 ns, 352 B, 4 allocs	~516 ns, 0 B, 0 allocs
SliceEqual string, 64 values	~677 ns, 384 B, 4 allocs	~474 ns, 0 B, 0 allocs
ChunkedEqual, 1,024 chunks x 64 values	~756 us, 360 KB, 4,096 allocs	~559 us, 0 B, 0 allocs

Tests

• go test ./arrow/array
• go test -race ./arrow/array
• go vet -composites=false ./arrow/array
• go test ./... -run '^$'
• GOOS=linux GOARCH=386 go test -c -o /dev/null ./arrow/array

[zeroshade]

Skipping slice construction for full-range inputs changes compatibility with arbitrary arrow.Array implementations.

The previous path normalized inputs through NewSlice/MakeFromData. The new fast path calls Equal directly, which panics for valid wrapper implementations it does not recognize. I reproduced this with a wrapper around *array.Int64; the same issue propagates through one-chunk ChunkedEqual. Details are inline.

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[zeroshade]

The full-range fast path calls Equal on the original interface values. Equal only handles Arrow-Go’s concrete array types or ExtensionArray, so another valid arrow.Array implementation now panics. Wrapping an *array.Int64 in struct{ arrow.Array } and calling full-range SliceEqual previously returned true; this head panics with arrow/array: unknown array type. Please retain the slice-normalization path for unsupported implementations or make Equal safely normalize generic arrays, and add the wrapper regression test.