Handling Token calculation from APIM for SSE Events

Following [this guidelines for sse in APIM](https://learn.microsoft.com/en-us/azure/api-management/how-to-server-sent-events#guidelines-for-sse) I'm trying to implement event hub logging to send the response of SSE events - *Azure OpenAI Streaming API* as I would like to [calculate the tokens](https://github.com/openai/openai-cookbook/blob/main/examples/How_to_stream_completions.ipynb), in my case there are multiple different clients/users and want to do this calculation on my side(APIM) so that I can tell the number of tokens are consumed by different clients/users.

The current policy will look like below.

```xml
@{return new JObject(
new JProperty("records", new JArray() {
new JObject(
new JProperty("EventTime", DateTime.UtcNow.ToString()),
new JProperty("ServiceName", context.Deployment.ServiceName),
new JProperty("RequestId", context.RequestId),
new JProperty("RequestIp", context.Request.IpAddress),
new JProperty("OperationName", context.Operation.Name),
new JProperty("response", context.Response.Body.As(preserveContent: true).ToString())
)
})).ToString();}
```

During the debug I could see it took a good amount of time to read the response payload (for sending to event hub)

```
{
"source": "response-payload-handler",
"timestamp": "2023-10-03T08:03:59.4607171Z",
"elapsed": "00:00:01.9290785",
"data": "Reading response payload because next handler requires access to it."
},
{
"source": "response-payload-handler",
"timestamp": "2023-10-03T08:04:05.1387406Z",
"elapsed": "00:00:07.6014120",
"data": "Reading response payload succeeded. 131316 bytes read."
},
```

If I remove below line
```
new JProperty("response", context.Response.Body.As(preserveContent: true).ToString()))
```

I don't see the `repose-payload-handler` task that is consuming a lot of time earlier. I also think due to implementing the eventhub for sending the response body, I suspect the streaming is not happening (checked from postman) It wait to give the full response till it completes the eventhub

Question is: Is there any way I could achieve this streaming (SSE Events) to log the response body async somewhere (event hub or servicebus ) without affecting the original streaming capability?

No repository files or tests are named. Start by reproducing the APIM policy with the log-to-eventhub policy and context.Response.Body.As(preserveContent: true), then compare SSE timing with and without response logging; done means the response streams without waiting for event-hub logging while the response data remains available for token calculation.

Written by the indexing model from the issue text.