feature: add oceanbase hybrid search support

[xxsc0529]

OceanBase Database is a completely self-developed enterprise-level native distributed database that supports vector storage and hybrid search, making it a powerful vector database.

close #1033

[andreibondarev]

@xxsc0529 Thank you for the addition. Unfortunately I'll be deprecating the Langchain::Vectorsearch::* set of classes and will be closing this PR. The concept of RAG had been replaced with broadly "context engineering" and, really, just context retrieval (not necessarily via vector search) which may or may find it way back into the library.