Pre render for quarto preview

[itepifanio]

Quarto provides pre and pos rendering features but it doesn't extend when live previewing the documents.

I have a script that reads yaml content and outputs .qmd files used in a Quarto website. I was trying to add a custom watcher for the yaml files, this way, when a yaml file changes the .qmd files the Quarto live previewing would refresh.

My solution was running Quarto as a subprocess and creating the custom watcher. A pre rendering that works with live previewing would make my life easier because I would be able to run the yaml watcher script without working with subprocessing.

[mcanouil]

Closing in favour of #4841