SL-17701 WIP -- Cleanup/refactor PBR lighting implementation and get parity between deferred and alpha passes for sunlight and IBL.

Further tweaking of directional shadow sampling to balance between peter-panning and shadow acne.

Move stars to just this side of the sky some to reduce parallax.

Remove decodeNormF and uses of decode_normal in favor of unified use of getNorm
(try to help the Intel HD x000 compiler learn to link correctly).

De-duplicate ambient occlusion shader code and move to new aoUtil.glsl

Split shared shadow tap funcs into shadowUtil.glsl

Modify handling of directional light to prefer sun when it is up but use moon dir/color when it is alone in the sky.

Modify handling of shader in shaders to get some shadowing of ambient and nighttime shadowing.

Eliminate 20+ callsites with copy-paste of getPosition and/or getNorm code.

Make pipeline use getShadowTarget/releaseShadowTarget consistently.

Remove moon_dir related shader code causing sunlight shadow artifacting.

Make env panel update environment when jumping frame to frame.

Add separate funcs for sun/moon vectors in various coord systems.

Make haze glow only pay attention to sun (i.e. fix sun glow when moon is near horizon in daytime).

FIXED