Verify the user-provided hostname in the server installer
    
    The refactor change 9094dfc had a slight error where the
    user-input provided value in input wasn't being validated. Only
    the command-line or the current FQDN was being verified so
    if the FQDN was bad any value input by the user was being skipped.
    
    Fixes: https://pagure.io/freeipa/issue/9111
    
    Signed-off-by: Rob Crittenden <rcritten@redhat.com>
    Reviewed-By: Florence Blanc-Renaud <flo@redhat.com>
    Reviewed-By: Florence Blanc-Renaud <flo@redhat.com>