.Net: Agents - CopilotStudioAgent not invoking AgentInvokeOptions.OnIntermediateMessage for non-streaming (#12589)

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Response always empty when using `CopilotStudioAgent` with any
`AgentOrchestration`

### Description
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Ability to use any `Agent` with an `AgentOrchestration` relies upon the
ability to recieve messages via the callback.

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Author: crickman

dotnet/src/Agents/Copilot/CopilotStudioAgent.cs

@@ -66,6 +66,12 @@ public override async IAsyncEnumerable<AgentResponseItem<ChatMessageContent>> In
         await foreach (ChatMessageContent result in invokeResults.ConfigureAwait(false))
         {
             await this.NotifyThreadOfNewMessage(agentThread, result, cancellationToken).ConfigureAwait(false);
+
+            if (options?.OnIntermediateMessage is not null)
+            {
+                await options.OnIntermediateMessage(result).ConfigureAwait(false);
+            }
+
             yield return new(result, agentThread);
         }
     }