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.
Looking at the service page on 3dbrew, the call has the code 0x00090040. Interpreting this acoording to the kernel IPC tag says that the call doesn't take any translate parameters. So the returned country code isn't even returned as a string pointer, it's returned inline. So the correct way of doing this would probably be `cmd_buffer[2] = code[0] | code[1] << 8`. Need to check if that's the order the characters are packed in, though.