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.
This looks a bit bad. I'd move the assembly of code to the declaration instead, so `u32 code = country_codes[i][1] | ...`.