Python: Add deprecaton warning to add_chat_message for server agents (microsoft#11331)

### Motivation and Context

Now that we have a common agent invocation API, that uses threads, we
will be deprecating the `add_chat_message` for the `AzureAIAgent` and
`OpenAIAssistantAgent`. Add the deprecation decorator and message.

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### Description

Add the deprecation decorator and message.

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These notes will help understanding how your code works. Thanks! -->

### Contribution Checklist

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- [X] The code builds clean without any errors or warnings
- [X] The PR follows the [SK Contribution
Guidelines](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
and the [pre-submission formatting
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raises no violations
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Author: moonbox3

python/semantic_kernel/agents/azure_ai/azure_ai_agent.py

@@ -5,6 +5,8 @@
 from collections.abc import AsyncIterable, Callable, Iterable
 from typing import TYPE_CHECKING, Any, ClassVar, Literal, TypeVar
 
+from typing_extensions import deprecated
+
 if sys.version_info >= (3, 12):
     from typing import override  # pragma: no cover
 else:
@@ -598,6 +600,9 @@ async def create_channel(self, thread_id: str | None = None) -> AgentChannel:
 
         return AzureAIChannel(client=self.client, thread_id=thread.id)
 
+    @deprecated(
+        "Pass messages directly to get_response(...)/invoke(...) instead. This method will be removed after May 1st 2025."  # noqa: E501
+    )
     async def add_chat_message(self, thread_id: str, message: str | ChatMessageContent) -> "ThreadMessage | None":
         """Add a chat message to the thread.
 

python/semantic_kernel/agents/open_ai/open_ai_assistant_agent.py

@@ -6,6 +6,8 @@
 from copy import copy
 from typing import TYPE_CHECKING, Any, ClassVar, Literal
 
+from typing_extensions import deprecated
+
 if sys.version_info >= (3, 12):
     from typing import override  # pragma: no cover
 else:
@@ -440,6 +442,9 @@ async def create_channel(self, thread_id: str | None = None) -> AgentChannel:
 
     # region Message Handling
 
+    @deprecated(
+        "Pass messages directly to get_response(...)/invoke(...) instead. This method will be removed after May 1st 2025."  # noqa: E501
+    )
     async def add_chat_message(
         self, thread_id: str, message: "str | ChatMessageContent", **kwargs: Any
     ) -> "Message | None":