rpm-ostree dnf info -> dnf info

[westurner]

rpm-ostree dnf info would be super convenient.

Also or instead, dnf info could work on rpm-ostree systems;
though as far as general dnf <command> support,
dnf commands that don't change anything (that do not mutate state) could work on rpm-ostree systems

Workarounds:

• rpm -q --whatprovides "${filepath}"
• rpm -qi "${pkgname}"
  • this only works for packages that are already installed,
    whereas dnf info pulls the package catalogs and
    lists both: "Installed packages" and "Available packages"
• Create a toolbox and run dnf in the toolbox container;
  toolbox create; toolbox run dnf info <path>
  • but a container may have a different distro+release or image
  • and probably has different different packages installed than the host
• rpm-ostree install dnf5
  • There is a reason that /usr/bin/dnf isn't already installed on rpm-ostree systems;
    but rpm-ostree calls into libdnf,
    so dnf info could work on rpm-ostree systems.

Tasks:

• Decide which of these if any:
• rpm-ostree info -> dnf info
• rpm-ostree dnf info -> dnf info
• rpm-ostree dnf {info,} -> dnf {}
  • dnf info doesn't change anything

[westurner]

• Add detection for ostree-based systems and warn users about losing changes rpm-software-management/dnf#2053
• https://github.com/rpm-software-management/dnf/pull/2053/files#diff-7fba0092ec8c6ecc5a8eb7458d9b713909a0fc27b5468f2e4d580ab333793564R217 :

  if dnf.util.is_container():