[Feature Request] Add toast entered animation

[dreamerblue]

You can use bottom left position to test. It looks very obvious.

The current Toast is only well animated when an element is removed from the container (the removed element slides out and the other elements follow and move to the correct position with animation).

However, when inserting a new element, only the new element has a slide-in animation, while all the other item's above that element move up instantly with no animation.

I'd suggest matching consistent animations for the other elements on entry, otherwise this looks like an imperfect flaw: beautiful animation only on deletion, but very stiff on insertion.