Translations:Hardcoded strings/2/vi

These difficulty level strings are used in the header row of the Other records table in TH07 and TH08. ZUN probably abbreviated Normal, Lunatic and Phantasm because an evenly spaced table with the unabbreviated names wouldn't fit on the screen with a 16 pixel MS Gothic. script_latin translates those using the unabbreviated names since its font is smaller.