following promotion of DRTVWR-573

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

to make it accessible after updating the viewer

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