dnf: RHEL, CentOS, Rocky, Alma, Fedora, Universal Blue

dnf support for nanolayer;

- "How to build tiny container images"
  https://www.redhat.com/en/blog/tiny-containers ::
  ```sh
  RUN dnf install -y busybox \
        && dnf clean all \
        && rm -rf /var/cache/yum
  ```
- https://www.redhat.com/en/blog/dnf-apt-users
- https://wiki.archlinux.org/title/Pacman/Rosetta