getFileSuffix static method
获取文件名后缀
Implementation
static String? getFileSuffix(String fileName, {bool keepDot = false}) {
String suffixName = p.extension(fileName);
if (isEmpty(suffixName)) return null;
if (keepDot) return suffixName;
if (suffixName.startsWith('.')) return suffixName.replaceFirst('.', '');
return null;
}