Replace create_vector_search_index

Remove create_vector_search_index from langchain-mongodb and import from
pymongo-search-utils.

Author: aclark4life

libs/langchain-mongodb/langchain_mongodb/index.py

@@ -6,6 +6,7 @@
 
 from pymongo.collection import Collection
 from pymongo.operations import SearchIndexModel
+from pymongo_search_utils import create_vector_search_index  # noqa: F401
 
 logger = logging.getLogger(__file__)