DRTVWR-559 Dynamic exposure followup -- stochastic sampling, weight based on luminance and distance to center of screen, rebalance night, don't rely on blending not clamping R16F.

SL-18563

DRTVWR-559 Fix for off-white metal not looking chromed when it should (fake hacky HDR sky reflections).

SL-18563

SL-19477 Remove angular attenuation from sphere probe weight to fix harsh indirect lighting.  Minor incidental decruft.

SL-19321 Optimization pass -- reduce occlusion culling frame stalls, reduce shadow draw distance in probes.

Fix for SL-18458 overrides not applying when cache load happened before LLViewerObject::updateTEMaterialTextures call

SL-19399: Allow editing all PBR texture transforms at once with Complete material radio

SL-19394: Update default midday per feedback

SL-19399: Reorganize controls for PBR material editing in the build floater in more sensible way. Ignore "Lock repeat" in PBR mode as it's redundant

SL-19394: Change default midday to an asset ID with probe ambiance

Phase 2 of work on SL-18458 material override cache fixes

DRTVWR-559 Quality pass -- Fix sky banding, fix off-by-one-mip in reflection probes (thanks Rye), remove noiseMap from light shaders (removes speckles), make irradiance maps RGB16F instead of RGBA16.  Use actual luminance for sky instead of max color component during irradiance map pass.

SL-19434: Fix texture issues with minimap, but keep performance from SL-19331