Integrate Material Design Feature Discovery for Chromecast

For:
- Chromecast support
  - Chromecast icons, see Templarian/MaterialDesign#2666
- What else?

See flutter/flutter#4296.

### Animated Cast Icon

- [Chromecast Cast button](https://developers.google.com/cast/docs/design_checklist/cast-button)
- [Cast to Chromecast Icon (Flutter Flare)](https://www.2dimensions.com/a/chance/files/flare/cast-to-chromecast/preview)