ls: fix alignment with locale formatted --size

ls: fix alignment with locale formatted --size

Fix allocated size alignment in locales with multi-byte grouping chars.
Tested with: LC_ALL=sv_SE.utf8 ls --size --block-size=\'k

* src/ls.c (print_file_name_and_frills): Don't rely on
printf("%*s", width, string) to pad multi-byte strings appropriately.
Instead work out the padding required and use:
printf("%*s%s", padding, "", string) to pad multi-byte appropriately.
* tests/ls/block-size.sh: Add a test case.
* NEWS: Mention the bug fix.
Fixes https://bugs.gnu.org/79347