Implement Snackbar v2 Component

Spec Reference: https://www.google.com/design/spec/components/snackbars-toasts.html 

It's been called a "Toast" in the past, but the thing that's not Android-specific is a **snackbar**.
- [x] Initial Implementation
- [ ] Dark Theme (background: `#fafafa`, text: text-primary-on-dark, action: theme primary color)
- [ ] Keyboard Focus Handling
