Introduce a dithering effect as you zoom out

[Garanas]

Prototype of a dithering-like effect for props.

https://github.com/FAForever/fa/assets/15778155/fb9bd357-2399-4a43-9783-cdf8527520aa

[BlackYps]

I just tested it and the effect seems promising. Trees in a half-transparent state are prone to a lot of flickering, so we should try to keep the transition period as small as possible. But if it is too short then it will feel instant again if you zoom fast, so we need to do some experimenting.