Python: Thread storage and serialization (#394)

* Updates for message store support

* Added unit tests

* Added suspend-resume example

* Added example with custom chat message store

* Small fix

* Addressed PR feedback

* Renaming and documentation

* More renaming

* Addressed more PR feedback

* Small fixes in Foundry chat client and examples

* Small update

* Addressed PR feedback

* Increased timeout for Azure tests

python/samples/getting_started/agents/azure_assistants_client/azure_assistants_with_thread.py

@@ -4,7 +4,7 @@ import asyncio
 from random import randint
 from typing import Annotated
 
-from agent_framework import ChatClientAgent, ChatClientAgentThread
+from agent_framework import AgentThread, ChatClientAgent
 from agent_framework.azure import AzureAssistantsClient
 from azure.identity import DefaultAzureCredential
 from pydantic import Field
@@ -95,7 +95,7 @@ async def example_with_existing_thread_id() -> None:
         print(f"Agent: {result1.text}")
 
         # The thread ID is set after the first response
-        existing_thread_id = thread.id
+        existing_thread_id = thread.service_thread_id
         print(f"Thread ID: {existing_thread_id}")
 
     if existing_thread_id:
@@ -108,7 +108,7 @@ async def example_with_existing_thread_id() -> None:
             tools=get_weather,
         ) as agent:
             # Create a thread with the existing ID
-            thread = ChatClientAgentThread(id=existing_thread_id)
+            thread = AgentThread(service_thread_id=existing_thread_id)
 
             query2 = "What was the last city I asked about?"
             print(f"User: {query2}")