Add transition fade when switching between crops

[cameronkruse]

I tried to implement this in this branch, but wasn't able to due to the fact it's using data-driven paint properties.

If we want to implement this as a feature we're going to need to get a hard coded layer attribute an change it in a way that makes the layer invisible, switch the styling and then make it visible. Deprioritizing for now, but keeping branch open if others have better ideas.