Enable onAnimationModalInEnd callback

[pichfl]

Closes #637

[pichfl]

@nickschot and I went on a wild chase Even though this "fixes" the issue, it most likely does so by covering up the actual problem while also introducing a lot of moving parts. My initial assumption that animationend might not trigger when a user enables prefers-reduce-motion is wrong, all tested browsers still trigger the event even if the animation time is reduced to 0s. If there is a "valid" animation, it will trigger the event.

Quoting MDN (emphasis by me):

The animationend event is fired when a CSS Animation has completed. If the animation aborts before reaching completion, such as if the element is removed from the DOM or the animation is removed from the element, the animationend event is not fired.

We want to make sure, that janking the model component still triggers all necessary parts, but we shouldn't do so by introducing timers. Instead #686 is most likely one of the problems behind #665

I'm keeping this PR open for reference until #665 is resolved.

[marcin-wicha]

Is anything blocking this currently? All of the referenced issues have been merged/closed.