certmonger: support dnsname as request search criterion
    
    We need to be able to filter Certmonger tracking requests by the DNS
    names defined for the request.  The goal is to add the
    'ipa-ca.$DOMAIN' alias to the HTTP certificate tracking requests, so
    we will use that name as a search criterion.  Implement support for
    this.
    
    As a result of this commit it will be easy to add support for subset
    match of other Certmonger request list properties.  Just add the
    property name to the ARRAY_PROPERTIES list (and update the
    'criteria' description in the module docstring!)
    
    Part of: https://pagure.io/freeipa/issue/8186
    
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>