date: width prefix in %N format specifier is ignored ( %3N, %6N always output full 9 nanosecond digits) #12001

[Devel08]

this PR closes #12001.
the %N format specifier was ignored when the default width value was greater than the specified one.

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/date/date-locale-hour (fails in this run but passes in the 'main' branch)
Skipping an intermittent issue tests/cut/bounded-memory (passes in this run but fails in the 'main' branch)
Note: The gnu test tests/basenc/bounded-memory is now being skipped but was previously passing.
Congrats! The gnu test tests/unexpand/bounded-memory is now passing!
Skip an intermittent issue tests/pr/bounded-memory (was skipped on 'main', now failing)

[Devel08]

Ready for review, however I found a small issue that is not connected to that Issue. GNU coreutils handles negative numbers such as +%mN where m is a negative number. I may open an issue about that when that one is resolved. Perhaps width should be isize and and effective_width should be the absolute value of width, so that it behaves like GNU coreutil does?

[cakebaker]

Thanks!