Update arxiv.py with get_summaries_as_docs inside of Arxivloader (#14953)

Added the call function get_summaries_as_docs inside of Arxivloader

- **Description:** Added a function that returns the documents from
get_summaries_as_docs, as the call signature is present in the parent
file but never used from Arxivloader, this can be used from Arxivloader
itself just like .load() as both the signatures are same.
- **Issue:** Reduces time to load papers as no pdf is processed only
metadata is pulled from Arxiv allowing users for faster load times on
bulk loads. Users can then choose one or more paper and use ID directly
with .load() to load pdf thereby loading all the contents of the paper.

libs/community/langchain_community/document_loaders/arxiv.py

@@ -25,3 +25,6 @@ class ArxivLoader(BaseLoader):
 
     def load(self) -> List[Document]:
         return self.client.load(self.query)
+
+    def get_summaries_as_docs(self) -> List[Document]:
+        return self.client.get_summaries_as_docs(self.query)