Add load() to snowflake loader (#5956)

Quick fix for recently added [snowflake data
loader](https://github.com/hwchase17/langchain/pull/5825/files).

langchain/document_loaders/snowflake_loader.py

@@ -118,3 +118,6 @@ def lazy_load(self) -> Iterator[Document]:
             metadata = {k: v for k, v in row.items() if k in metadata_columns}
             doc = Document(page_content=page_content, metadata=metadata)
             yield doc
+
+    def load(self) -> List[Document]:
+        return list(self.lazy_load())