Add openai_client as property and update notebook. (#654)

* Initial commit

* Add code interpreter notebook.

* Update code interpreter notebook.

* Update notebook.

* Update agentchat_oai_code_interpreter.ipynb

* Update agentchat_oai_code_interpreter.ipynb

* Add openai_client as property.

---------

Co-authored-by: Chi Wang <wang.chi@microsoft.com>
Co-authored-by: Qingyun Wu <qingyun.wu@psu.edu>

autogen/agentchat/contrib/gpt_assistant_agent.py

@@ -341,6 +341,10 @@ class GPTAssistantAgent(ConversableAgent):
         """Return the assistant id"""
         return self._openai_assistant.id
 
+    @property
+    def openai_client(self):
+        return self._openai_client
+
     def get_assistant_instructions(self):
         """Return the assistant instructions from OAI assistant API"""
         return self._openai_assistant.instructions