OPEN-340 & OPEN-343 - Consolidate shader atmospheric calcs into a singular utility shader + fix fog on fullbright in deferred

SL-10925, SL-10926, SL-10896

New fix for 925/926 that doesn't cause 896 again.

Also linearize moon disc tex color.

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branch : OPEN-340

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branch : OPEN-340

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branch : OPEN-340

Given that mShaderObjects only ever expects one copy of a given shader object (leading to lots of "shaderV" and "shaderF"), it made having utility shaders a bit more difficult to incorporate.
This change makes sure the two are separated.  Using this over a multimap largely for readibility.

Also, actually, you know, use this functionality.

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branch : OPEN-340

Still some work to go here.  Largely related to how certain values (i.e., SSAO mix values) are supplied.  But so far, so good.

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branch : OPEN-340

Fix falloff on projectors in forward rendering (different falloff calcs than deferred).

Restore letting env auto-update sunlight_color uniform (other shaders expect it even if lighting does not).

Make projector ambiance unshadowed in both forward and deferred for consistency.

SL-10912

Fix conversion of star brightness, density mult, and distance mult to legacy ranges.

Make settings look in both legacyhaze and top-level settings for haze params.

Add decls for intermediate lighting values for debug.

SL-10821, SL-10896, SL-10901

Fix deferred water soften prog lightnorm getting stomped with rotated lightnorm,
because it's a water shader and needs water atmo uniform values,
but it's a deferred lighting shader that needs not-so-rotated lightnorms.

Make sunlight_color not get auto-updated so we can get the correct value from mSunDiffuse.

Remove mix to preserve bumps as it was washing out shadows.

Fix directionality of da and preserve bumps on completely shadowed areas.

SL-10748

Clamp far_clip for sun shadows to >= 256.0 to prevent issues when draw distance < ~100m.

SL-10854

Clamp ambient to keep shadows dark.

Apply min with shadow value after we've pow'd by light gamma consistently between forward and deferred.

Clamp ambient contrib to get darker shadows.

New PCF sampling func.

SL-10887

Disable occlusion culling when rendering water reflection/refraction maps again (still getting probabalistic results for reflection map contents). :/

SL-10886

Render sun/moon beacons in non-ALM mode too.

SL-10875 FIXED [EEP] Selecting the Day Cycle window causes the previous keyframe to become selected if keyframes are close together

Fix for BUG-226620

Approved-by: Graham Madarasz <graham@lindenlab.com>

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branch : BUG-226620

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branch : BUG-226620

Fixes BUG-226620

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branch : BUG-226620