SL-19015 Balance sun/sky ambiance with punctual light ambiance.  Prevent irradiance maps from being brighter than the environment.

SL-19015 Bump probe resolution back to 256 by default (drop to 128 if vram < 2GB), remove irradiance map feedback loop (one bounce, but but more stable and allows for much brighter first bounce), make sky contribution to irradiance not tint the world blue.  Make irradiance that appears in radiance maps match world irradiance.

* SL-19203 WIP -- Integrate SSR with reflection probes.  Decruft LLRenderTarget.

* SL-19203 WIP -- Re-integrate SSR.  Incidental decruft.

* SL-19203 WIP -- SSR frame delta correction (still broken for Z)

* SL-19203 WIP -- SSR frame delta Z fix

* SL-19203 WIP -- Make SSR toggleable again and disable SSR in cube snapshots.

* SL-19203 WIP -- Soften sphere probe transitions and fix reflections on void water (make fallback probe a simple terrain+water+sky probe).  Remove parallax correction for automatic probes to reduce artifacts.

* SL-19203 Tune probe blending.

* SL-19203 Cleanup.

SL-19081: Fix assert when uploading texture

SL-19012: Fix new material IDs sometimes not applying when set via LSL

SL-19014 Sanitize the override data sent for faces without GLTF materials

Attempt to simplify and avoid use of GL_UNSIGNED_INT_8_8_8_8_REV where not needed

SL-18869 Followup -- leverage "small commands" and time slicing to get rid of frame stalls on main thread without the need for multithreaded GL

SL-18869, SL-18772  Overhaul VBO management, restore occlusion culling, intel compatibility pass, etc