Auto load fonts on demand

[aszenz]

Is your feature request related to a problem? Please describe.

Using different fonts in a template is currently difficult. As a developer using this library idk which fonts my users are going to use in their templates.

Users can use different fonts in their templates, and it's hard to know ahead of time which fonts are required to render the template, loading all the supported fonts is inefficient.

Describe the solution you'd like

Download/load selected fonts on demand.

Let's say the user has typed #set text(font: "Arial", size: 10pt, hyphenate: true) in their template, when compiling try to download and load the Arial font from a configurable server endpoint (default to Google fonts).

Describe alternatives you've considered

• A separate method to extract fonts used in a template that the user can then preload.

Additional context

I'm building an app to render invoice templates for different customers, they will use commonly used fonts.

[cog25]

Related: #412