allow fmt_flag() method to handle internal error when 2 or 3 letter ISO is not available

[Yasin197]

currently the fmt_flag() method only takes 2 or 3 letter country codes and errors when that code is not recognized. we should accommodate a way to still render the column flags if they are correct and exist as then we can style the rows which did not render as a flag successfully.

there is a way in the method to specify which index rows to allow the render