Add streaming of prompt flow responses

[teebu]

Is your feature request related to this sample app, or to an Azure service, such as Azure OpenAI or Azure AI Search?
Enable streaming responses from prompt flow.

Is your feature request related to a problem? Please describe.
Streaming of regular requests is working, but it would be great if prompt flow response were also streamed to improve responsiveness of chat.

Describe the solution you'd like
Implement https://learn.microsoft.com/en-us/azure/machine-learning/prompt-flow/how-to-enable-streaming-mode?view=azureml-api-2

Is this feature specific to your use case or your organization, or would it apply broadly across other uses of this app?
Streaming makes things feel snappier.