[BREAKING] Python: Refactor workflow events to unified discriminated union pattern (#3690)

* Refactor events

* Merge main

* Fixes

* Cleanup

* Update samples and tests

* Remove unused imports

* PR feedback

* Merge main. Add properties for events to help typing

* Formatting

* Cleanup

* use builtins.type to avoid shadowing by WorkflowEvent.type attribute

* Final improvements

python/samples/demos/workflow_evaluation/create_workflow.py

@@ -48,12 +48,10 @@ from _tools import (
 from agent_framework import (
     AgentExecutorResponse,
     AgentResponseUpdate,
-    AgentRunUpdateEvent,
     ChatMessage,
     Executor,
     WorkflowBuilder,
     WorkflowContext,
-    WorkflowOutputEvent,
     executor,
     handler,
 )
@@ -355,7 +353,7 @@ async def _process_workflow_events(events, conversation_ids, response_ids):
     workflow_output = None
 
     async for event in events:
-        if isinstance(event, WorkflowOutputEvent):
+        if event.type == "output":
             workflow_output = event.data
             # Handle Unicode characters that may not be displayable in Windows console
             try:
@@ -364,7 +362,7 @@ async def _process_workflow_events(events, conversation_ids, response_ids):
                 output_str = str(event.data).encode("ascii", "replace").decode("ascii")
                 print(f"\nWorkflow Output: {output_str}\n")
 
-        elif isinstance(event, AgentRunUpdateEvent):
+        elif event.type == "output" and isinstance(event.data, AgentResponseUpdate):
             _track_agent_ids(event, event.executor_id, response_ids, conversation_ids)
 
     return workflow_output