ipatests: check HTTP certificate contains ipa-ca.$DOMAIN dnsname
    
    Add integration test that confirms that on CA-ful installation, the
    (non-3rd-party) HTTP certificate bears the ipa-ca.$DOMAIN DNS name.
    
    For detailed discussion on the purpose of this change and the design
    decisions made, see `git log -1 $THIS_COMMIT~4`.
    
    Part of: https://pagure.io/freeipa/issue/8186
    
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>