tar: Move to the utilities package

tar(1) is not a core runtime utility; in particular, nothing in
/etc/rc.d/* requires it. Move it to utilities, which is also
where cpio(1) lives.

This removes the dependency from runtime to libarchive.

MFC after: 3 days
Reviewed by: manu, emaste
Sponsored by: https://www.patreon.com/bsdivy
Differential Revision: https://reviews.freebsd.org/D53059