bodhi_comment_directive: log_url can point to ResultsDB status page
    
    Now that we have artifacts that only contain the 'sane' subset of tests' output,
    lets change the URL in Bodhi-comment, so it points to the respective ResultsDB's
    result page, from which it is then possible to either go to the log, or view the
    other results.
    
    In order to do that, it is necessary for the resultsdb_directive to produce
    information about item->result_id pairing. After a discussion with @kparal
    I've added another reserved key to the TAP's YAML section - `__internal`.
    The value is meant to be a dictionary, that will contain the implementation
    specific bits of information, when we need to transfer data from one directive
    to another.
    
    Differential Revision: https://phab.qadevel.cloud.fedoraproject.org/D395