The prefix string for qdrant collection is now
configurable, which means the same qdrant cluster
can be used to host more open webui instances and
to be able to separate the collections between the
different owui instances.
- Created `VectorDBBase` as an abstract base class to standardize vector database operations.
- Added required methods for common vector database operations: `has_collection`, `delete_collection`, `insert`, `upsert`, `search`, `query`, `get`, `delete`, `reset`.
- The base class can now be extended by any vector database implementation (e.g., Qdrant, Pinecone) to ensure a consistent API across different database systems.
