feat(theme): add new property mixin and custom property support
feat(theme): add new property mixin and custom property support

These changes are meant to bring about better first-class support for custom properties and dynamic theming.

BREAKING CHANGE: `color-hash()` (and checkbox container-colors mixins) no longer works with `var()` values and now only works with custom property Maps created by `custom-properties.create()`

PiperOrigin-RevId: 313825202

material-components/material-web,material-components/material-web