CFG:U: Implemented the GetCountryCodeID and GetCountryCodeString

I couldn't find a way to retrieve all the country code strings, and the ones in there need to be checked, probably using a real 3DS.
Does the 3DS send those strings with a NULL terminator? that's another thing that has to be checked on a real 3DS.
I used apt_u.cpp as example, the functions there are not static either, should I change it here?