The grpc_client_stream maybe crash when the connection was closed

`grpc_client_stream` maybe crash when the connection was closed.

`grpc_client_stream.erl`

```erlang
rst_stream(#{connection := Connection,
             stream_id := StreamId} = Stream, ErrorCode) ->
    grpc_client_connection:rst_stream(Connection, StreamId, ErrorCode),
    Stream#{state => closed}.
```