The Nishita sky texture currently only allows moving the sun to the zenith.
The problem is if you want to animate the passing of a full night-day-night
cycle. Currently it's not easy to do due to this limitation.
The patch makes it so users can easily animate the sun moving from sunrise
to sunset by expanding the max sun elevation to go 360° instead of 90°.
Reviewed By: fclem
Differential Revision: https://developer.blender.org/D13724
ad5e3d30a2