prefers-reduced-motion props

[flavienbonvin]

Currently, animations are played regardless of the prefers-reduced-motion preferences. This can be an issue when working on accessibility.

Having a prop on the useRive hook that would control how the animation behaves when prefers-reduced-motion is true would be great. Besides, it could be great to define a frame or a fallback image when prefers-reduced-motion is true. This way it would be possible to display the first or last image or have a fallback image instead.