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.
What was wrong with the original approach? cmd_buff is u32, and country_code is u16, this isn't safe.