Add support to export a DOT diagram of the internal guts of the highlighter.

Stakeholders: Cirrus Engineers
Outcome: David will get his feet wet in the highlighter and will have a chance to ask Nik questions before he goes. And we can make some pretty pictures, but that isn't super important.
Estimate: 1 or 2 days

There are few real user facing tasks around the highlighter - certainly few things we need. Some folks on the internet are asking for true span query support and that would be nice to finish the query_string_plus_plus_plus work but that is a bigger task and not _strictly_ required for query_string_plus_plus_plus anyway.