Core: Animations respect `prefers-reduced-motion` OS setting

Using animations on the web in the most accessible way requires a little extra consideration:

In general, it's best to use animations on the web in a complementary way rather than the only way to note a state change in UI. Remember to update the text of actions and change elements' other visual aspects too!

And when it comes to an animation's timing and duration, avoid changing the state of something at a rate of three times per second or greater - which can trigger photosensitive epilepsy.

All included animations now support and leverage the prefers-reduced-motion CSS media feature (opens new window)to detect if a user has requested that the system minimize the amount of non-essential motion it uses.

When a prefers-reduced-motion is set to reduce, it indicates that the user prefers less motion, which may trigger discomfort for those with vestibular motion disorders on the page.

Review the repository's included animations and the CSS prefers-reduced-motion media feature described in the issue. Verify how animations behave when the setting is reduce, and consider the work complete when all included animations minimize non-essential motion without being the only way to communicate a state change.