[fix](azure-iot-device-mqtt): remove double nesting on sendEvent TransportObj

[YoDaMa]

This is in reference to #626

The wrapping of the response was 1) redundant and 2) out of line with how other MQTT calls are made.

With this change an MQTT PUB and ACK look like this:

  azure-iot-mqtt-base:MqttBase CONNACK: {"cmd":"connack","retain":false,"qos":0,"dup":false,"length":2,"topic":null,"payload":null,"sessionPresent":false,"returnCode":0} +1ms
...
  azure-iot-device-mqtt:Mqtt PUBACK: {"cmd":"publish","topic":"devices/beta/messages/events/IMPACT_EMERGENCY=false","payload":"{\"size\":26.15078342292594,\"timeTillImpact\":22.72007917052823}","qos":1,"retain":false,"messageId":10181,"dup":false} +2s

Before (without this change):

  azure-iot-mqtt-base:MqttBase CONNACK: {"cmd":"connack","retain":false,"qos":0,"dup":false,"length":2,"topic":null,"payload":null,"sessionPresent":false,"returnCode":0} +1ms
...
  azure-iot-device-mqtt:Mqtt PUBACK: {"transportObj":{"cmd":"publish","topic":"devices/beta/messages/events/IMPACT_EMERGENCY=false","payload":"{\"size\":49.08919394567126,\"timeTillImpact\":57.049220217156815}","qos":1,"retain":false,"messageId":48866,"dup":false}} +6s

This resolves the unnecessary double nesting that occurred on message responses, which was a bug.

[YoDaMa]

test needed.

[anthonyvercolano]

[anthonyvercolano]

/azp run horton-node-gate