CheckPassword checks the password strength.

DecodeAndCheckImageFile currently answers support image type is `image/jpeg, image/jpg, image/png, image/gif, image/webp`.

IsNotZeroString check s is not empty string and is not "0".

IsQuestionsIgnorePath checks whether the questionID is in ignore path.

IsReservedUsername checks whether the username is reserved.

IsUnAuthorizedExtension check whether the file extension is not in the allowedExtensions WANING Only checks the file extension is not reliable, but `http.DetectContentType` and `mimetype` are not reliable for all file types.

IsUsersIgnorePath checks whether the username is in ignore path.