Support using different fonts

[PullJosh]

Right now, converted projects always use Times New Roman for text in an svg sprite, even if that's not correct.

[FunctionalMetatable]

You can probably inject the style outputted by scratch-render-fonts. Also note that scratch-paint doesn't actually support fonts in exported svgs

[PullJosh]

Oh, fascinating! I didn't know about that. It could be helpful!

[valadaptive]

See https://github.com/valadaptive/sb3-js/blob/main/src/load-svg.ts as a reference