ffi: create data source from memory buffer

[myrrc]

Match rust API: buffer is borrowed under the condition it won't be modified
until data source is freed.

We need this for ClickHouse integration as it hands us memory buffers.

[codspeed-hq]

Merging this PR will improve performance by 12.48%

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⚡ 1 improved benchmark
✅ 1544 untouched benchmarks
⏩ 10 skipped benchmarks¹

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Simulation	encode_varbin[(1000, 2)]	176.7 µs	157.1 µs	+12.48%

Tip

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_{Comparing myrrc/ffi-read-from-buffer (8429479) with develop (2528dca)}

Footnotes

1. 10 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. ↩

[AdamGS]

Seems reasonable to me, but maybe needs someone with more C/FFI opinions.

[0ax1]

Couple of nits and questions.

[m7kss1]

this approach implies that the data is already in ram, but in ch read buffer is a streaming abstraction, including positional read api over s3/ssd etc. wouldn't it be more reasonable to exposeVortexReadAt to ffi?

[myrrc]

I agree, but this is a separate work which is non-trivial as opposed to this function. I have it on my TODO list. The issue with this is that we already have an inverse abstraction (duckdbfs) which we probably want to pull out.

[myrrc]

#8433