Add CSS Animation library

[BinaryMoon]

Inspiration from here:
https://css-tricks.com/a-handy-little-system-for-animated-entrances-in-css/
https://animista.net/
https://easings.net/
https://animate.style/

Simple subtle animations only. Keep it to four or five of them. Including modifiers for animation delay

[woodcox]

If you are just wanting some simple animations you could pull in the animations.scss from open-props-scss. I recently closed an issue there to add the animations. Just waiting for Mayank to update npm. This repo is a programmatic sass conversion of open-props.