🍱 Add additional fonts

[aaronleopold]

Resolves #377

I've added the following:

• Atkinson Hyperlegible
• Charis SIL
• Literata
• Libre Baskerville
• Nunito

I had to add a really annoying hack because of epub.js in order to get the fonts to render correctly, but it seems to be working alright. I'll also add that the fonts sit around 10MB now, which is fairly high. I'll likely not add anymore for the foreseeable future.

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 6 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
core/src/db/entity/user/preferences.rs	50.00%	6 Missing ⚠️

Files with missing lines	Coverage Δ
core/src/db/entity/user/preferences.rs	78.69% <50.00%> (-2.20%)	⬇️