This still needs some work - I'm not super satisfied with the overall structure of the code.  Will continue to iterate as I add in proper RenderDoc support.

SL-18239 Unify PBR and non-PBR treatment of ambient/SSAO/irradiance.  Restore SSAO to release version.

SL-18190 End of linear space odyssey -- just eat the conversions in atmosphericsFuncsF for sunlight and additive, but leave linear ambient in tact.

SL-18190 WIP -- Take 2 on linear space windlight (more methodical approach -- make desired interface but brute force color conversions). Placeholder PBR water and move to deprecate forward rendering shaders.

SL-18190 WIP - Windlight to linear space proof of concept, better parity between release viewer and materials viewer when reflections disabled.  Avoid run-away probe ambiance.

SL-18120 Fix for specular color of legacy materials tinting environment reflections from "environment" intensity.

SL-17705 Backwards compatibility pass.  Support OpenGL pre-4.0 by disabling reflection probes and anti-aliasing.  Get render parity with current release viewer when reflection probes are disabled.

And a fix to prevent message spam