localedata: add some exceptions to utf8proc widths

Hangul Jamo medial vowels and final consonants are reportedly combining
characters that won't take up any columns on their own and should be
reported as zero-width, so add an exception for these as well to reflect
how they work in practice. This conforms to how other implementations
(e.g., glibc) treat these characters.

Reviewed by: bapt (earlier version), jkim
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D47472