Drop or clarify color.emphasis

[gadenbuie]

We might want to make this cleaner and use color.bold and color.italic, or at least clarify how it should be used.

[gadenbuie]

emphasis came from Bootstrap colors:

Emphasis — For higher contrast text. Not applicable for backgrounds.

This maps to $body-emphasis-color in Bootstrap

[gadenbuie]

I think we should drop color.emphasis now and see if there's demand for a feature like this.

[cscheid]

(FYI - I'm tracking all outstanding schema changes for Quarto in https://github.com/quarto-dev/quarto-cli/tree/feature/brand-yaml-schema-consolidation/. It won't be on main until I merge, but you can follow the branch if needed)

This is fixed in Quarto by quarto-dev/quarto-cli@c5c98f2