Add fprintd-pam to a new critical-path-standard group
    
    We had a situation with an fprintd update that broke su and
    console logins:
    https://bodhi.fedoraproject.org/updates/FEDORA-2020-f997de7d0e
    so clearly fprintd should be on the critical path. This is my
    best guess as to how we should best do this (will discuss
    details in the PR).
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>