patch DHCP NM dispatcher for distribution
    
    Patch the upstream example `nm-dispatcher.dhcp` with
    Fedora/RHEL-specific behavior including exiting if a dhclient
    install is detected, and using the /etc/sysconfig paths.
    
    Originally part of work for fixing integration between the
    NetworkManager internal DHCP client and chrony:
    https://bugzilla.redhat.com/show_bug.cgi?id=1800901