Charts: inject wpds fallbacks during build

[simison]

WIP

Depends either on WordPress/gutenberg#80401 which adds LightningCSS plugin for WPDS fallbacks in wp-theme, or switching to PostCSS.

Similar to one done for social-previews in #50646

Proposed changes

• Lints against adding wpds token fallbacks in CSS
• Removes manually added WPDS fallbacks from CSS and JS
• Configures LightningCSS (WIP) and Vite plugins from @wordpress/theme to add fallbacks during build time.

Related product discussion/links

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Testing instructions

*WIP

[github-actions]

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[github-actions]

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Code Coverage Summary

This PR did not change code coverage!

That could be good or bad, depending on the situation. Everything covered before, and still is? Great! Nothing was covered before? Not so great. 🤷

Full summary · PHP report · JS report