[android] Missing icon results in warning in Play Store on tablets

# Bug Report

## Problem

### What is expected to happen?
The application appears as usual in Google Play store

### What does actually happen?
On tablets there is the warning "This app may not be optimised for your device" in Google Play store entry of the application

## Information

This warning appears if assets are added which don't support tablets. You can see in the res folder of Android that there are icons for HDPI, MDPI, XHDPI and XXHDPI. XXXHDPI is missing which is required for tablets.
More information about that can be found [here](https://developer.android.com/docs/quality-guidelines/tablet-app-quality#use-tablet-icons).

### Command or Code

### Environment, Platform, Device

Samsung TAB S2 (Android 7)

### Version information

Cordova CLI: 8.1.2
cordova-android: 7.1.4

## Checklist

- [x] I searched for existing GitHub issues
- [ ] I updated all Cordova tooling to most recent version
- [x] I included all the necessary information above

Inspect the Android res folder and compare the existing HDPI, MDPI, XHDPI, and XXHDPI icon assets with the Android tablet icon guidance linked in the issue. Add the missing XXXHDPI tablet asset, then verify that the application no longer triggers the Google Play tablet-optimization warning.

Written by the indexing model from the issue text.