charmap: Add korean hangul and vietnamese pronunciations

Add vietnamese (kVietnamese) and korean pronunciation in hangul
(kHangul) to the unicode data.

Add vietnamese pronunciation to the charmap character details page,
and replace the kKorean use with kHangul use for korean since
kHangul is recommended to be used over kKorean by UAX#38.

http://www.unicode.org/reports/tr38/
https://bugzilla.gnome.org/show_bug.cgi?id=773380