perf: Optimize comparison on nested types

[neilconway]

Which issue does this PR close?

N/A

Rationale for this change

BooleanBuffer::collect_bool() is faster than map().collect(). Per discussion on #20694; originally suggested by @Dandandan.

What changes are included in this PR?

• Implement optimization
• Add benchmark for nested struct comparison

Are these changes tested?

Yes, covered by existing tests.

Are there any user-facing changes?

No.

AI usage

Multiple AI tools were used to iterate on this PR. I have reviewed and understand the resulting code.

[neilconway]

Benchmarks:

  group                          base                                   target
  -----                          ----                                   ------
  compare_nested array_array     1.17     52.5±0.78µs        ? ?/sec    1.00     44.8±0.27µs        ? ?/sec
  compare_nested array_scalar    1.12     50.1±0.38µs        ? ?/sec    1.00     44.6±0.30µs        ? ?/sec

[alamb]

Makes sense to me -- thanks @neilconway

I do wonder why we can't update collect to call collect_bool internally 🤔