Fixed LightProbes to have gamma correct when using gamma color space

[lukaschod]

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Purpose of this PR

Fix for case https://fogbugz.unity3d.com/f/cases/1268911/.

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Testing status

Manual Tests: What did you do?

• Opened test project + Run graphic tests locally
• Built a player
• Checked new UI names with UX convention
• Tested UI multi-edition + Undo/Redo + Prefab overrides + Alignment in Preset
• C# and shader warnings (supress shader cache to see them)
• Checked new resources path for the reloader (in developer mode, you have a button at end of resources that check the paths)
• Other:

Automated Tests: Can not really add automation as we are currently testing linear color space only. Part of discussion is here https://unity.slack.com/archives/C89KFUUCT/p1596718321327600?thread_ts=1596617214.309600&cid=C89KFUUCT.

Yamato: https://yamato.prd.cds.internal.unity3d.com/jobs/902-Graphics/tree/universal%252Fbugfix%252Flight-probes-gamma-space

Test Project: Added in the case https://fogbugz.unity3d.com/f/cases/1268911/.
Linear

Gamma before fix

Gamma after fix

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Comments to reviewers

As we always had incorrect LightProbe contribution in gamma space, this fix will change the look of current projects. Can we do something to make this easier for users?

[pbbastian]

Code looks good. I think this makes sense to land even if it changes existing projects, but we should land it in a new major version. That also means it shouldn't be backported.

Since this is a behavior change, can you add something to the "Changed" section in the change log? Keep the bug fix note in fixed as well though.

[phi-lira]

I agree with Peter, imo we can still land this for 10.x as is preview as long as we land for 10.1. Please add changed in the section as well and ready-to-merge tag when ABV is green.

[lukaschod]

Code looks good. I think this makes sense to land even if it changes existing projects, but we should land it in a new major version. That also means it shouldn't be backported.

Since this is a behavior change, can you add something to the "Changed" section in the change log? Keep the bug fix note in fixed as well though.

Added changed entry, will try to land into 10.1 if not will post-pone it to next major.

[lukaschod]

So as I understand we are still in 10.1.x preview, maybe we can land it?