feat(scan): Support RHEL8

[kotakanbe]

What did you implement:

• repoquery
  https://dnf.readthedocs.io/en/latest/command_ref.html#repoquery-command-label
  repoquery --upgrades --qf=‘%{NAME} %{EPOCH} %{VERSION} %{RELEASE} %{REPONAME}’ -q

• (removed in RHEL8)yum-plugin-ps
  https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html-single/considerations_in_adopting_rhel_8/index

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

scan RHEL8 with fast or fast-root mode.

Checklist:

You don't have to satisfy all of the following.

• Write tests
• Write documentation
• Check that there aren't other open pull requests for the same issue/feature
• Format your source code by make fmt
• Pass the test by make test
• Provide verification config / commands
• Enable "Allow edits from maintainers" for this PR
• Update the messages below

Is this ready for review?: YES