Consider using custom presentation controller for popup interaction and animation

[LeoNatan]

https://developer.apple.com/library/content/featuredarticles/ViewControllerPGforiPhoneOS/DefiningCustomPresentations.html

https://developer.apple.com/library/content/featuredarticles/ViewControllerPGforiPhoneOS/CustomizingtheTransitionAnimations.html#//apple_ref/doc/uid/TP40007457-CH16-SW2

Currently for #211, I have implemented the animation using UIViewPropertyAnimator. It's buggy and doesn't behave as expected under certain cases. Also, people have requested that view appearance be communicated to the popup hosting controller.

I think I could simplify some of the presentation and transition code inside the framework by switching to using a custom presentation controller and an interactive presentation animator.

[LeoNatan]

Closing in favor of #348.