[WIP][RFC] Support streaming response.

[SuZhou-Joe]

Is your feature request related to a problem?
Dashboard assistant does not support streaming response, users have to wait for the whole response to complete. With the streaming response, user can see the result earlier and can pause if the response does not meet their needs.

What solution would you like?

Solution A: Event stream API to communicate with Server

Solution B: Use fetch with readable stream.

What alternatives have you considered?
A clear and concise description of any alternative solutions or features you've considered.

Do you have any additional context?
Add any other context or screenshots about the feature request here.

[krisfreedain]

Catch All Triage - 1, 2, 3