[HDRP][URP][SpeedTree8] Set shadergraph as default SpeedTree 8 shader for Universal. Clean up HDRP importers/upgraders.

[nerites]

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Purpose of this PR

• Sets the PBRLit SpeedTree 8 ShaderGraph as the default SpeedTree 8 shader for Universal.
• Updates the URP ST8 test scene to use the ShaderGraph and have more usable error thresholds
• Fixes the core SpeedTree8 material upgrader to properly handle common keyword-to-float and float-to-float renames.
• Updates the HD SpeedTree8 material upgrader to handle _CullModeForward and streamlines code.

The new SpeedTree 8 test scene in URP_Terrain is arranged so that the trees take up a larger proportion of the test image. Previously the trees were very small and failures would only get flagged when enough diffs had accumulated that the visual differences were very obvious.

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Testing status

Tested that both importing SpeedTree8 assets and upgrading from builtin works correctly. This is best done by verifying that billboard keywords and wind quality get the expected values on the Billboard material for a Palm asset, since the Palm wind quality and the Billboard being enabled are non-default values.

Importing HDRP:

Upgrading HDRP:

Importing URP:

Upgrading URP:

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Comments to reviewers

Do I need to backport to 21.1?

[github-actions]

Hi! This comment will help you figure out which jobs to run before merging your PR. The suggestions are dynamic based on what files you have changed.
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HDRP
/.yamato%252Fall-hdrp.yml%2523PR_HDRP_trunk
With changes to HDRP packages, you should also run
/.yamato%252Fall-lightmapper.yml%2523PR_LightMapper_trunk

URP
/.yamato%252Fall-urp.yml%2523PR_URP_trunk
With changes to URP packages, you should also run
/.yamato%252Fall-lightmapper.yml%2523PR_LightMapper_trunk

Shader Graph
/.yamato%252Fall-shadergraph.yml%2523PR_ShaderGraph_trunk
Depending on your PR, you may also want
/.yamato%252Fall-shadergraph_builtin_foundation.yml%2523PR_ShaderGraph_BuiltIn_Foundation_trunk
/.yamato%252Fall-shadergraph_builtin_lighting.yml%2523PR_ShaderGraph_BuiltIn_Lighting_trunk

SRP Core
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[nerites]

The failures in the XR tests look like resolution inconsistencies that were not occurring before I merged SRP master two days ago :/ Reasonably sure the Metal failure is spurious, but I'm still waiting on rerun. Opening for reviews now.

[JMargevics]

Hello, pulled latest and could not reproduce errors anymore. All works well now, can't see any importer regressions on my side. Upgrading builtin assets also had no issues 👍✔

[Nightmask3]

Approving

[simon-engelbrecht-soerensen]

Tested with upgrading URP and converting from Built in to URP. Both seems to work.

[phi-lira]

Merged master to run PR URP as many issues that were failing are not fixed.
@nerites is there a path to upgrade the hand written speedtree8 to the shader graph one?

[phi-lira]

Failures seem instabilities. I re-kicked some jobs to be sure but approving for now.