Feature request: exit stream successfully after receiving N responses

hi, I'm trying to use gRPCurl in some automated API test suite, and I'm not sure what the best way to test response-streaming RPC methods. I would like to call the method, make sure the stream starts, and then gracefully cancel the stream with a success code (assuming everything actually works until that point).

so far, what I've found is the flag `-max-time`, which limits how long gRPCurl is subscribed to the stream, but then it closes with an ERROR:
```
Code: DeadlineExceeded
Message: Deadline Exceeded
```

would it be possible to add an option like `-max-response N`, which only applies to response-streaming RPCs, and then cancels the stream gracefully once the desired number of responses has been received by gRPCurl?

thanks!

Start with gRPCurl's existing `-max-time` option and the response-streaming RPC call path. Determine how the CLI reports stream termination, then verify that the requested response count ends successfully in an automated API test suite rather than with `DeadlineExceeded`.

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