Use specific font for Japanese
Because of Han Unification, GUI installer don't render Japanese typeface (glyph) correctly for a long time since Debian 9 (stretch)
As it takes extra disk usage, use compressed font for Japanese. MotoyaLCedar is good enough balance with point of view of disk usage, readability and visibility.
See https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1037256
NOTE: This change additionally requires to support compressed font and updated rootskel-gtk.