.Net: Change ChatCompletionAgent to notify intermediate messages as soon as they are available.

[westey-m]

Motivation and Context

Addresses #12521

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the SK Contribution Guidelines and the pre-submission formatting script raises no violations
• All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄

[rogerbarreto]

Suggest adding a UT ensuring this behavior

[westey-m]

Suggest adding a UT ensuring this behavior

Sure, will look at this separately.

[GrillPhil]

@westey-m I still have this issue with the current version 1.60.0-preview of Microsoft.SemanticKernel.Agents.AzureAI
IntermediateMessages e.g. tool calls are arriving AFTER responses.

public async IAsyncEnumerable<AgentStreamingContent> Prompt(
        string prompt)
    {
        AzureAIAgent agent = await CreateAzureAIAgentWithTools().ConfigureAwait(false);
        Channel<AgentStreamingContent> channel = Channel.CreateUnbounded<AgentStreamingContent>();

        AzureAIAgentThread agentThread = new(agent.Client);
        AgentInvokeOptions agentInvokeOptions = new()
        {
            AdditionalInstructions = toolOptionsText,
            OnIntermediateMessage = (message) =>
            {
                foreach (KernelContent content in message.Items)
                {
                    if (content is Microsoft.SemanticKernel.FunctionCallContent functionCallContent)
                    {
                        Console.WriteLine($"FunctionCallContent Plugin {functionCallContent.PluginName}, Function {functionCallContent.FunctionName}");
                    }
                    else if (content is Microsoft.SemanticKernel.FunctionResultContent functionResultContent)
                    {
                        Console.WriteLine($"FunctionCallContent Plugin {functionResultContent.PluginName}, Function {functionResultContent.FunctionName}");
                    }
                    else
                    {
                        // Handle other content types if necessary
                    }
                }
                return Task.CompletedTask;
            }
        };

        async Task InvokeStreaming()
        {
            Microsoft.SemanticKernel.ChatMessageContent message = new(AuthorRole.User, prompt);
            await foreach (StreamingChatMessageContent response in agent.InvokeStreamingAsync(message, agentThread, options: agentInvokeOptions).ConfigureAwait(false))
            {
                if (!string.IsNullOrEmpty(response.Content))
                {
                    Console.WriteLine($"StreamingChatMessageContent {response.Content}");
                }
            }
        }

        Console.WriteLine($"Invoking streaming");
        Task.Run(async () => await InvokeStreaming());
    }

[westey-m]

@GrillPhil, this fix was on the ChatCompletionAgent, but it looks like you are using an AzureAIAgent here right?

[GrillPhil]

@GrillPhil, this fix was on the ChatCompletionAgent, but it looks like you are using an AzureAIAgent here right?

Yes exactly. The events come in the right order on AzureAIAgent when I user InvokeAsync but at the end when using the streaming API.

[westey-m]

Thanks @GrillPhil, I've opened a new bug to address this across all agent types.
See #12789