ShadowCaster now using varyings normalWS for shader graph

[Nzollner]

Purpose of this PR

This PR is needed in order to use changed normals in the shadow caster if they are updated in the fragment shader. Otherwise will the normal bias break the shadows.

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Testing status

I have tested the fix with the project given in the bug and tested if the universal graphics tests worked locally.

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Comments to reviewers

Notes for the reviewers you have assigned.

[github-actions]

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[pbbastian]

LGTM

[simon-engelbrecht-soerensen]

LGTM