Use an unsafe trait to reinterpret packed struct references as bytes

[AdamGS]

Summary

This is a cosmetic change to make it clearer what is happening when re-interpreting references as raw bytes to serialize plans, making it harder to mis-use by making it a more specific trait.

[codspeed-hq]

Merging this PR will improve performance by 20.65%

⚡ 1 improved benchmark
✅ 1121 untouched benchmarks
⏩ 1530 skipped benchmarks¹

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Simulation	chunked_bool_canonical_into[(1000, 10)]	60.2 µs	49.9 µs	+20.65%

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_{Comparing adamg/unsafe-packed-bytes-trait (178a612) with develop (95befa7)}

Footnotes

1. 1530 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. ↩