Solas Shader

Features added/changed:

+ Added screen space ambient occlusion and shadows. Both work on normal terrain, Distant Horizons and Voxy LODs. Screen space shadows also extend the regular shadows even without Voxy or DH.
+ Reworked planar clouds to look more like real life cirrus clouds
+ Improved lighting on the ender protoplanetary disk
+ Improved blending between different sky effects
+ Improved red aurorae. Now they are way more saturated
+ Made cloud shadows a bit softer

Features fixed:

+ Fixed shader failing to load on versions of Iris below 1.19.2
+ Fixed some compatibility errors on 1.12.2
+ Fixed volumetric clouds clipping through Voxy LODS
+ Fixed water artifacts with Voxy
+ Fixed water disappearing at 2 chunks render distance
+ Fixed end flashes not working correctly with Voxy
+ Fixed exponential fog noise taking very weird shapes
+ Fixed several compilation errors when toggling different options

Features removed:

- 512 shadowmap resolution. It makes no sense, really