expose highlight.js options via frontmatter

[hesxenon]

Is your feature request related to a problem? Please describe.
Currently I'm unable to find a way to enable highlighting for less used languages (fsharp in my case). Highlight.js supports fsharp, but it has to be explicitly enabled. Afaik the only way to do this is via the initial configure call.

Describe the solution you'd like
It'd be nice to have a frontmatter property like highlightLanguages: ['typescript', 'fsharp', 'java']

Describe alternatives you've considered
Including custom JS and using reveal.js' api directly. Too much effort, too many presentations to write^^

Additional context
I'm fairly certain I managed to do this at some point in the past, just unsure whether that was back when I used my own version of reveal.js or not 🤔