Fix irradiance gen up vector to be properly normalized

SL-18065 WIP -- Adjust max virtual size to keep debug floater readable.  Make assert on shutdown less frequent (still not gone, likely race condition).  Fix unrelated assertion in reflection probes.

SL-17523 Add reflection probe ambiance to windlight settings and integrate with UI and ReflectionMapManager

SL-17574 Add probe detail combo box to advanced graphics preferences.  Fix spot light shadows not working in probes.

SL-17287 Instrument and optimize cubemap render.  Fix for cubemap snapshots doing a full resolution render instead of a 512x512 render.

SL-17283 LLReflectionMapManager prototype.  Remove snapshot code related overhead from reflection map renders.  Add parallax correction and support for multiple reflection maps.