Python: [Breaking] Simplified Content types to a single class with classmethod constructors. (#3252)

* ported Content to a new model

* fixed linting

* fixes

* fixed data format handling

* fix for 3.10 mypy

* fix

* fix int test

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

@@ -9,7 +9,7 @@ from agent_framework import (
     AgentRunUpdateEvent,
     ChatClientProtocol,
     ChatMessage,
-    Contents,
+    Content,
     Executor,
     Role,
     WorkflowBuilder,
@@ -155,7 +155,7 @@ class Worker(Executor):
 
         if review.approved:
             print("Worker: Response approved. Emitting to external consumer...")
-            contents: list[Contents] = []
+            contents: list[Content] = []
             for message in request.agent_messages:
                 contents.extend(message.contents)