[BREAKING] Python: Add factory pattern to GroupChat and Magentic (#3224)

* group chat

* magentic

* Fix tests

* AI comments

* Unifiy error message and add warning

* misc

* Add overload

* Collapse orchestrator params

python/samples/getting_started/workflows/agents/group_chat_workflow_as_agent.py

@@ -34,8 +34,8 @@ async def main() -> None:
 
     workflow = (
         GroupChatBuilder()
-        .with_agent_orchestrator(
-            OpenAIChatClient().as_agent(
+        .with_orchestrator(
+            agent=OpenAIChatClient().as_agent(
                 name="Orchestrator",
                 instructions="You coordinate a team conversation to solve the user's task.",
             )

python/samples/getting_started/workflows/agents/magentic_workflow_as_agent.py

@@ -56,7 +56,7 @@ async def main() -> None:
     workflow = (
         MagenticBuilder()
         .participants([researcher_agent, coder_agent])
-        .with_standard_manager(
+        .with_manager(
             agent=manager_agent,
             max_round_count=10,
             max_stall_count=3,