[C++][Compute] Investigate prefix-aware early rejection for StringView equality kernels #55254

Describe the enhancement requested

In #55171, direct comparison kernels were added between StringView and standard offset-based string types.

As noted by @dmitry-chirkov-dremio in PR review, equality comparisons involving StringView can leverage the 4-byte inline prefix stored in the 16-byte view descriptor (e.g. via util::EqualBinaryView or inline prefix checks against offset strings) to reject mismatches without dereferencing payload buffers.

A prototype demonstrated roughly 1.8x–2x speedups on workloads with ~50% early mismatches. However, because prefix checking adds overhead when strings match, incorporating this requires broader benchmarking and tuning of adaptive heuristics (such as batch sampling thresholds).

This issue tracks benchmarking and exploring prefix-aware fast paths for equal / not_equal kernels across BinaryView / Utf8View types.

Component(s)

C++