Animate the opening of apps from the 'Applications' menu

## Problem

When a user opens an app the Applications menu in elementary OS (which is the only place where apps are permanently stored, added or removed), they have to wait until the app opens, and 💥️ **bang!** 💥️ an app's window just appeared! Who knows where it came from?
It's kinda dumb that only mobile and tablet OSes fully animate the opening of apps to show where they are opening from.

## Proposal

At least for elementary apps, the main window should swoop in from the top left corner where the 'Applications' menu indicator is. The animation could be incredibly simple, it doesn't need to be a genie animation like minimising in macOS is. All it needs to do is animate the app's window scaling and swooping from the top left of the screen, and then animate an image of the app's last state swooping back when it is closed.
As for when the 'Applications' menu is open, either don't animate at all or try to animate the app scaling out of its icon.

## Prior Art

https://user-images.githubusercontent.com/58219504/107858978-b938f200-6e2e-11eb-9c53-28b4d364f7c5.mov