[Feature] In-Memory Vector DB Integration

[kuraleta]

As a java developer, I want to be able to use local (in-memory/persistent) vector store/DB:

• I don't want to depend on external services
• I want to keep things simple
• I don't need to keep a lot of information
• I want to be able to cache some responses from external vector DB to speedup search/retrieval

Requirements:

• Ability to store vectors (embeddings) and make a search with different similarity algorithms
• In-memory / persistent (e.g. file)

Check this:

• https://weaviate.io/
• https://www.trychroma.com/
• https://milvus.io/blog/in-memory-replicas.md
• https://github.com/jelmerk/hnswlib/blob/master/hnswlib-examples/hnswlib-examples-java/src/main/java/com/github/jelmerk/knn/examples/FastText.java
• JFastText Facebook
• ELKI
• Apache Lucene + similarity function