Create SMS.lng_KO for Korean

[DDinghoya]

Pull Request checklist

Note: these are not necessarily requirements

• [ ] I reformatted the code with clang-format
• [ ] I checked to make sure my submission worked
• [ ] I am the author of submission or have permission from the original author
• [ ] Requires update of the PS2SDK or other dependencies
• [ ] Others (please specify below)

Pull Request description