duckdb: Reset validity instead of filling

[myrrc]

1. Reset validity if it's "all true" instead of filling manually.
2. Set validity to true if parent array is constant (slicing won't affect that).
3. Reset validity if buffer after copying is all ones or all zeroes.
4. Copy validity mask and count ones in one pass

[codspeed-hq]

Merging this PR will not alter performance

✅ 1122 untouched benchmarks
⏩ 1455 skipped benchmarks¹

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_{Comparing myrrc/duckdb-validity (7658463) with develop (ac87fe0)}

Footnotes

1. 1455 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[joseph-isaacs]

NICEE