Jsonnet language syntax support

[zalegrala]

Motivation

I'd like to write an article about Jsonnet, but I see there is no support for this langugage in Prism. It would be nice to have syntax highlighting for all the normal reasons.

https://jsonnet.org/ref/spec.html

Description

As a slightly niche langugage for configuration, it might be nice to have more articles support this syntax so that we can tell folks the joy of using it. :)

If nobody wants to pick this up, perhaps folks can help steer me in the right direction, and I can make a PR that attempts this, though I've not written a prism spec highlighter before.

Alternatives
Live without syntax highlighting.