bug#64420: string-width of … is 2 in CJK environments

[Eli Zaretskii]

> Cc: 64420@debbugs.gnu.org
> Date: Fri, 14 Jul 2023 09:58:42 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> 
> By default, Emacs already treats the ellipsis as a Narrow character,
> and our current idea of "context" is the value of
> language-environment, when the font information is not available.
> Since Emacs doesn't currently support language tags or any other
> feature which would allow the language to change on a per-buffer or
> per-text region basis, the best we can do to allow finer-tuned width
> of these characters is some kind of user customization, which assumes
> that users know better which fonts are used by Emacs and by terminal
> emulators they use for the Emacs TTY frames.

Would someone please go over the characters whose width is marked as
"ambiguous" ("A") in Unicode's EastAsianWidth.txt file, and tell which
ones of them we should make single-column, when the above mentioned
user options tells us to default to "narrow"?  I think all those up to
codepoint #x324F should be treated like that, but maybe I decided
wrong?

TIA