feat: LSH for in memory vector store

[Dev79844]

Fixes: #760

• Added support for LSH using random projections approach
• Modified vector store methods for configuring index strategy

[joshua-mo-143]

Hi @Dev79844, great work on this! I'll be reviewing sometime during the week.

[joshua-mo-143]

Some general comments:

• Overall, pretty good work.
• I think we need a builder for InMemoryVectorStore and provide IndexStrategy::BruteForce as the default (which will prevent breaking changes from needing to adjust the current from methods).
• I am not hugely sold on the enum because it causes strange implementation behaviour (like having to fall back to brute forcing in vector_search_lsh when there's no LSH index), but as it's mostly internal implementation we can figure this out later on. InMemoryVectorStore is not really supposed to be used for huge production stuff anyway.

[Dev79844]

Hey @joshua-mo-143!
After adding builder, should index_strategy argument be removed from the from methods?

[joshua-mo-143]

Hey @joshua-mo-143! After adding builder, should index_strategy argument be removed from the from methods?

Yeah index strategy should be removed.

The idea is that we provide good defaults for users to fall back to, and then when they want to use the higher-power options they can switch to it (so in this case we'd default to IndexStrategy::BruteForce to prevent breaking changes in behaviour).

[joshua-mo-143]

Some minor stuff to be fixed, mostly just comment reworking/removal and some clarification for users who find the LSH stuff and have no idea how to use it