Change linefeed codes from "\r\n" to "\n" in Korean message catalogs

[kazuhitoyokoi]

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Proposed changes

I found that Korean message catalogs use "\r\n" as a linefeed code.

Because "\n" is the default in the Git environment, I think it is a little difficult to check the difference between commits. In this pull request, I have changed the linefeed codes from "\r\n" to "\n".

Checklist

• I have read the contribution guidelines
• For non-bugfix PRs, I have discussed this change on the forum/slack team.
• I have run grunt to verify the unit tests pass
• I have added suitable unit tests to cover the new/changed functionality