Explain the query AST to users via an interactive generated UI

[RunDevelopment]

This feature request is inspired by regexr.com's explain feature. The website has an interactive generated UI that explains any regex in more human-understandable terms. It basically explains the syntax of every regex.

This could be very useful for Netspeak users after we bring Antlr4 to our website. The website would then explain queries in a similar fashion. This is a lot more friendly than a link to a query example page or the spec of Netspeak queries.

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This feature, while not too complex to implement, is fairly low-priority at this point in time.