[FEAT]: Add openGauss as a DB provider

[SetnameWang]

What would you like to see?

openGauss is a new vector DB. Official website is:
https://opengauss.org/en/

openGauss recently updated its DataVec vector engine:

DataVec currently supports two index structures, IVFFlat and HNSW, to accelerate vector similarity queries. IVFFlat (Inverted File Flat) is an index structure based on inverted files, suitable for fast retrieval of large datasets. HNSW (Hierarchical Navigable Small World) is a graph-based index structure that enables efficient approximate nearest neighbor search in high-dimensional spaces.