Azure IoT SDKs for Node.js v1.15.0

• refactor: expose connection error in mqtt (#776)
• chore: remove network_e2e directory - no longer used (#775)
• refactor: update to mqtt.js v4 (#772)

The release exposes TLS Errors on connect in MQTT and upgrades the core MQTT.js dependency to v4

Package versions

azure-iot-common@1.12.2
azure-iot-amqp-base@2.4.2
azure-iot-http-base@1.11.2
azure-iot-mqtt-base@1.12.1
azure-iot-device@1.15.0
azure-iot-device-amqp@1.12.2
azure-iot-device-http@1.12.2
azure-iot-device-mqtt@1.14.0
azure-iothub@1.12.2
azure-iot-provisioning-device@1.8.2
azure-iot-provisioning-device-http@1.8.2
azure-iot-provisioning-device-amqp@1.8.2
azure-iot-provisioning-device-mqtt@1.7.2
azure-iot-provisioning-service@1.8.2
azure-iot-provisioning-device-e2e@1.8.2
azure-iot-security-x509@1.7.2
azure-iot-security-tpm@1.8.2
azure-iot-security-symmetric-key@1.7.2