The new semantic color scheme includes a number of new properties focused on their contextual use within components. This should make it easier to provide consistent, holistic theming for an entire app using a set of baseline colors and mappings.
* `primaryColor` - Displayed most frequently across your app.
* `primaryColorVariant` - A tonal variation of primary color.
* `secondaryColor` - Accents select parts of your UI.
* `backgroundColor` - The underlying color of an app’s content.
* `errorColor` - The color used to indicate error status.
* `surfaceColor` - The color of surfaces such as cards, sheets, menus.
* `onBackgroundColor` - A color that passes accessibility guidelines for text/iconography when drawn on top of `backgroundColor`.
* `onPrimaryColor` - A color that passes accessibility guidelines for text/iconography when drawn on top of `primaryColor`.
* `onSecondaryColor` - A color that passes accessibility guidelines for text/iconography when drawn on top of `secondaryColor`.
* `onSurfaceColor` - A color that passes accessibility guidelines for text/iconography when drawn on top of `surfaceColor`.
**New Catalog Component**

Closes https://github.com/material-components/material-components-ios/pull/3134