bug#41250: 28.0.50; Dired displays unconditionally ls-switches on modeline

[Juri Linkov]

> Would anybody mind very much if I added a `string-truncate-right' that
> does all this automatically, and amend `string-truncate-left' in the
> same way?  I.e., use (if (char-displayable-p ?…) "…" "...").

There is a better function 'truncate-string-to-width'.

But users need to set up 'truncate-string-ellipsis' explicitly
in init files as

  (with-eval-after-load 'mule-util
    (setq truncate-string-ellipsis "…"))