UTF-8 progress bar

[Julien Lepiller]

Hi Guix!

I have a patch waiting (https://issues.guix.gnu.org/59975) that will
change progress bars to use some unicode characters. I think they look
better, but I'm a bit afraid they might not look right on some config,
so I'd like to know if your terminal is able to show these characters:

"▏▎▍▌▋▊▉█▏▕"

If you are not using a unicode locale, this change will not affect you
as guix will fallback to the ascii style. If your terminal can't show
these characters and you have a UTF-8 locale (you'd run echo $LANG to
know that), please report your config (name of terminal app, locale,
fonts, …)!