CLEARTEXT communication not permitted by network security policy

### Problem description

When running `tabris serve --logging` and then attempting to connect with an Android 9 device, the following error is seen on the device:

```plain
CLEARTEXT communication to 192.168.1.x not permitted by network security policy
```

The server's request log shows no requests.

Opening `http://192.168.1.x:8080/` in a browser on the same Android device shows:
```
Tabris.js CLI version 3.0.0-rc1-dev.20190416 is running
```

### Environment

- Tabris.js version: `3.0.0-rc1-dev.20190416`
- Device: Pixel 3
- OS: Android 9

---

The APK was generated from a bare project created with `tabris init` and then built using the cloud build service without adjusting any of the build settings

Reproduce the issue with `tabris serve --logging` and the bare project created by `tabris init` on Android 9. Start by comparing the generated APK's network security behavior with the browser's successful HTTP access, using the cloud-build settings as the entry point. Done means the generated app can connect to the local server without the cleartext-policy error.

Written by the indexing model from the issue text.