overwriteDefaultIcons 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 overwriteDefaultIcons(IosIconTemplate template, Image image, [String iconNameSuffix = '']) {
final Image newFile = createResizedImage(template, image);
File(iosDefaultIconFolder + iosDefaultIconName + iconNameSuffix + template.name + '.png')
..writeAsBytesSync(encodePng(newFile));
}