Add qdrant - a vector similarity search engine

[janriemer]

This adds qdrant - a vector similarity search engine with extended filtering support. Categories are clustering and data-structures (analog to the crate faiss). URL: https://github.com/qdrant/qdrant The crate is not hosted on crates.io.

[llogiq]

While Qdrant itself is not hosted on crates.io, the Rust client is: https://crates.io/crates/qdrant-client

[janriemer]

@llogiq Oh, interesting! Normally, I don't say this, but: Thank you for the pointer (pun intended)! 😜