Add unit tests for agents

- Add permutations of testing for with, without knowledge base. Private, public, different users.

tests/conftest.py

@@ -178,6 +178,13 @@ def api_user4(default_user4):
     )
 
 
+@pytest.mark.django_db
+@pytest.fixture
+def default_openai_chat_model_option():
+    chat_model = ChatModelOptionsFactory(chat_model="gpt-4o-mini", model_type="openai")
+    return chat_model
+
+
 @pytest.mark.django_db
 @pytest.fixture
 def offline_agent():