ls: implement --group-directories-first

[thomasqueirozb]

Closes #3519

[sylvestre]

Cool stuff. Could you please add tests? thanks

[thomasqueirozb]

Cool stuff. Could you please add tests? thanks

I did it but I went down a rabbit hole. I found out that ls -a doesn't work the same as the GNU version. The . and .. directories are always first, no matter what. If sorts are applied, -r is specified or --group-directories-first is used, the location of . and .. shouldn't always be on the top.

Now with the changes I made it mostly behaves the same (I think). But this created one unfortunate side effect: ls -a1v now places .. at the end of the list and . at the beginning. The GNU version places both . and .. at the beginning. I couldn't find an easy fix for this so I just changed the test.

[sylvestre]

I went down a rabbit hole.

Welcome to the Rust/coreutils ;)

[thomasqueirozb]

An unrelated test failed. Maybe re-run that step of the CI?

[sylvestre]

bravo
Warning: Congrats! The gnu test tests/ls/group-dirs is no longer failing!