addTileOverlay does not render tiles on the iOS or android devices

**I'm submitting a ...** (check one with "x")
- [ ] question
- [X] any problem or bug report
- [ ] feature request

**If you choose 'problem or bug report', please select OS:** (check one with "x")
- [X] **Android**
- [X] **iOS**
- [ ] **Browser**

**cordova information:** (run `$> cordova plugin list`)

```
com.googlemaps.ios 3.9.0 "Google Maps SDK for iOS"
cordova-android-support-gradle-release 3.0.1 "cordova-android-support-gradle-release"
cordova-plugin-advanced-http 2.5.1 "Advanced HTTP plugin"
cordova-plugin-buildinfo 2.0.3 "BuildInfo"
cordova-plugin-camera 4.1.0 "Camera"
cordova-plugin-device 2.0.3 "Device"
cordova-plugin-facebook4 6.4.0 "Facebook Connect"
cordova-plugin-file 6.0.2 "File"
cordova-plugin-geolocation 4.0.2 "Geolocation"
cordova-plugin-globalization 1.11.0 "Globalization"
cordova-plugin-googlemaps 2.7.1 "cordova-plugin-googlemaps"
cordova-plugin-ionic 5.4.7 "cordova-plugin-ionic"
cordova-plugin-ionic-keyboard 2.2.0 "cordova-plugin-ionic-keyboard"
cordova-plugin-ionic-webview 4.2.1 "cordova-plugin-ionic-webview"
cordova-plugin-network-information 2.0.2 "Network Information"
cordova-plugin-sign-in-with-apple 0.1.2 "cordova-plugin-sign-in-with-apple"
cordova-plugin-splashscreen 5.0.4 "Splashscreen"
cordova-plugin-statusbar 2.4.3 "StatusBar"
cordova-plugin-telerik-imagepicker 2.3.5 "ImagePicker"
cordova-plugin-whitelist 1.3.4 "Whitelist"
cordova-sqlite-storage 3.4.1 "Cordova sqlite storage plugin - cordova-sqlite-storage plugin version"
cordova-universal-links-plugin 1.2.1 "Universal Links Plugin"

```

**If you use `@ionic-native/google-maps`, please tell the package.json (only `@ionic-native/core` and `@ionic-native/google-maps` are fine mostly)**

**Current behavior:**
On iOS or Android, if I add a tileOverlay, it does not render. Only the underlying google maps is shown. However, on cordova browser it works perfectly.

**Expected behavior:**
I see the tile overlay

**Related code, data or error log (please format your code or data):**

```
this.map = GoogleMaps.create('map_canvas', mapOptions);
this.map.addTileOverlaySync({
getTile: (x, y, z) => `https://tiles.stadiamaps.com/tiles/alidade_smooth/${z}/${x}/${y}@1x.png`
});
```

Reproduce the issue on iOS and Android using the shown addTileOverlaySync call and compare it with the working Cordova browser behavior. Trace the native handling of addTileOverlaySync and its getTile callback; done means the Stadia Maps tile overlay renders on both native platforms.

Vom Indexierungsmodell aus dem Issue-Text verfasst.