[Design System] Deprecations, linting, and helpers

[antonjoel82]

What changed? Why was the change needed?

• Deprecate old design-system concepts that should now be done through design tokens
• Add helpers for getting the color scheme
• Add linting for direct imports of @mantine/core in web
• Add Netlify configurations to the toml -- we were implicitly linting (all of web, not just changed files) during deploy-preview builds, which I don't think we should be doing. This also has the added benefit of giving us version control to these commands