Bringing Geospatial Filtering and Vector Search Together with Geometry Fields and RTREE in Milvus 2.6

Introduces the Geometry Field (DataType.GEOMETRY) for storing spatial data (Point, LineString, Polygon) using WKT format. Implements an RTREE index for efficient spatial filtering through coarse and fine filtering stages, supporting operators like st_contains, st_within, and st_dwithin. Enables joint retrieval by combining RTREE-based spatial filtering with vector similarity search, allowing for spatially aware intelligent retrieval.