Support use library import to import fonts and other files

[ogoffart]

Discussed in #7085

^{Originally posted by mcitem December 13, 2024}

I think using relative paths will eventually turn into a disaster.
I hope to import other resource files (such as fonts) through aliases just like importing Slint, similar to the path aliases in Vite.
https://vite.dev/config/shared-options.html#resolve-alias

[tronical]

Ah, indeed, it looks like we're trying to parse the .otf file as Slint source code, instead of recognising it as a font to be imported.