breaking(go): update flow streaming protocol to SSE

[hugoaguirre]

curl -X POST -H "Accept: text/event-stream" http://localhost:3400/streamy -d '{"data":5}'
data: {"count":0}

data: {"count":1}

data: {"count":2}

data: {"count":3}

data: {"count":4}

data: {"result": "done: 5, streamed: 5 times"}\n

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[pavelgj]

this needs to be wrapped in a {"message": ...} object.

[pavelgj]

Suggested change

	_, err := fmt.Fprintf(w, "data: %s\n\n", msg)
	_, err := fmt.Fprintf(w, "data: {"message": %s}\n\n", msg)

[hugoaguirre]

Thanks Pavel, adding the changes now