[DocDB] Integrate vector search indexes into RocksDB

Jira Link: DB-10645

Approach:

The normal SSTable files store key/value mappins of the form id -> vector (id could be ybctid of the primary table, or something else)
Next to each SSTable file, we generate the vector search file (IVFFLAT, HNSW or other type of index) using the appropriate library, such as FAISS or Usearch.
On the read path, we can provide the vector in read options, and Seek/Next will navigate the result set of the vector search, which could be consumed by the downstream DocDB framework in the usual manner.

kind/enhancement

yugabyte / yugabyte-db