saveNewIcons function
Note: Do not change interpolation unless you end up with better results (see issue for result when using cubic interpolation) https://github.com/fluttercommunity/flutter_launcher_icons/issues/101#issuecomment-495528733
Implementation
void saveNewIcons(IosIconTemplate template, Image image, String newIconName) {
final String newIconFolder = iosAssetFolder + newIconName + '.appiconset/';
final Image newFile = createResizedImage(template, image);
File(newIconFolder + newIconName + template.name + '.png')
.create(recursive: true)
.then((File file) {
file.writeAsBytesSync(encodePng(newFile));
});
}