feat: teach ALPRDArray how to append_to_builder

[danking]

The PrimitiveBuilder API is a bit awkward for this. I needed two key things:

1. I want to treat a trailing slice of the builder's values as a different type. In particular, ALPRD decodes u32s (respectively u64s) and then converts them to f32s (resp. f64s).

2. I want to separately update the nulls and the values. In particular, ALPRD stores the nulls on the left parts whereas the right parts hold the values.

All of this is copacetic when done on the UninitRange, but I do it on the whole PrimitiveBuilder. I kinda think PrimitiveBuilder should be able to split itself into the initialized and uninitialized parts. In my opinion, it seems reasonable to transmute the builder of uninitialized parts since no one else is looking at that data anyway.

[codspeed-hq]

Merging this PR will improve performance by 96.1%

⚡ 5 improved benchmarks
✅ 949 untouched benchmarks
⏩ 1466 skipped benchmarks¹

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Simulation	alp_rd_decompress_f64	27.4 ms	18.5 ms	+48.16%
⚡	Simulation	decompress_rd[f32, 100000]	1,873.8 µs	955.5 µs	+96.1%
⚡	Simulation	decompress_rd[f32, 10000]	256.6 µs	164.4 µs	+56.06%
⚡	Simulation	decompress_rd[f64, 100000]	2.3 ms	1.4 ms	+64.43%
⚡	Simulation	decompress_rd[f64, 10000]	262.3 µs	171.6 µs	+52.88%

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_{Comparing dk/alprd-decode-into-builder (50b4af9) with develop (e0ce169)}

Footnotes

1. 1466 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. ↩