Adding new features to the Typst template

[christopherkenny]

This implements the changes suggested in #9956, with the exception of the filecolor/urlcolor one. These would require adding some regex to guess the link types. This is theoretically possible to do, but it wasn't clear to me that this is a good thing to put in a default template. Happy to adjust if you have thoughts on this.

Some things to note:

• I'm converting colors by passing them as content, as I was seeing pandoc escape # if that was included. An alternative here is to just do something like: rgb(linkcolor.replace("\\#", "#")).
• I set the default fonts for math and code ("raw") to fonts that are bundled with Typst. These need not be those fonts if there are more familiar pandoc preferences.