Add benchmark for n-dimensional khash (from UCX)

[alex--m]

Based on the new n-dimensional ANN lookup implemented in UCX (based on khash).

[maumueller]

Thanks for the contribution. I am a bit unsure how this is supposed to work, where will the *. so file come from? Please provide a dockerfile in install/ and add your implementation to CI in .github/ to see if it works. Thanks!

[alex--m]

@maumueller Yes, there are some open technical issues, and that's why I've submitted it as a "draft PR". To clarify, this runs on my machines, but the best way to go is to only merge this after UCX accepts the implementation code upstream (may take a while...) - then this libucs_ann_search.so is distributed as part of the UCX installation (in a container). The reason I did create this PR (aside from future reference) is for the UCX community to see and play with evaluating the performance of this ANN implementation, to convince them to accept it).

[maumueller]

@alex--m: Thanks for the explanation. Looking forward to the progress.

[erikbern]

I agree with @maumueller – I think it should come with a proper Dockerfile