SL-20440 Fix for projector ambiance destroying PBR shading.  Also fix longstanding bug with hard line in projector ambiance lighting.  Incidental decruft of legacy_adjust and LOCAL_LIGHT_KILL, etc.

SL-20141 Remove "Local Lights" checkbox and instead make the number of lights rendered scale with the "Quality & speed" slider

Pulled in relevant parts from SL-19929

To make multiple parallel features possible

SL-19567: (WIP) Add options to use higher precision for glow and post-process buffers. Disabled by default.

Also tweak our vignette to help (further) skip samples we don't need, and for further look and feel adjustments.
SL-19784

SL-19784

SL-19784

SL-19784

SL-19808: Fix orientation of PBR normal texture when texture transform and/or texture animation is applied

DRTVWR-559 Revert skies to be very close to release and disable tone mapping when probe ambiance is zero.

Hack for desaturating legacy materials has been removed for performance and quality reasons.

Adds a new setting for auto adjusting legacy skies.  This is the PBR "opt out" button.  If disabled, legacy skies will disable tonemapping, automatic probe ambiance, and HDR/exposure.  If enabled, legacy skies will behave as if probe ambiance and HDR scale are 1.0, and ambient will be cut in half.  

HDR scale will act as a sky brightener, but will automatically adjust dynamic exposure so the sky will be properly exposed.  If you want relatively even exposure all the time, set HDR Scale to 1.0.  If you want a high range of exposures between indoor/dark areas and outdoor/bright areas, increase HDR Scale.

Also tuned up SSAO (thanks Rye!).

Reviewed with Brad.

DRTVWR-559
DRTVWR-583

SL-19713 Fix for broken avatar preview render in animation upload.  Incidental decruft and camera FoV network spam reduction.

* Fix water fog mismatch between alpha blend and opaque when local light is nearby

* Add PBR underwater alpha blend shader

DRTVWR-559 Remove RenderReflectionProbeCount (which is bugged) and lean on RenderReflectionProbeLevel for preferences (which works).