[OP-200] Move fonts to their own files

[Jeremy-Walton]

Why?

Moving the font imports to their own files allows for better organizing, overriding, customizing, and clearer documentation.

What Changed

• Move font imports out of icon and base tokens and into core/fonts/text_fonts.css and core/fonts/icon_fonts.css
• Update selective imports documentation
• Update file organization documentation
• Update comments in documentation code examples to use the correct syntax
• Update dependency notes and the graph to include the fonts

Sanity Check

• [ ] Have you updated any usage of changed tokens?
• Have you updated the docs with any component changes?
• Have you updated the dependency graph with any component changes?
• Have you run linters?
• Have you run prettier?
• Have you tried building the css?
• Have you tried building storybook?
• [ ] Do you need to update the package version?

Screenshots

[linear]

OP-200 Move font imports to their own folder