Add Blender Cycles, using Principled BSDF 2.0, to the render fidelity test

### Description

Add Blender Cycles using its latest Principled BRDF 2.0 to the Render Fidelity Test page. This will allow us to compare glTF PBR rendering in Blender Cycles with all of the other renderers featured on the fidelity page now.

My recommendation on implementing this is to use the Blender Python interface that allows you to use Blender from the command line via Python. You should set up the various backgrounds using the assets provided by model-viewer and then use the Blender Khronos glTF importer to import the various gltF assets and then render the images using Python. Thus it is one or more of python scripts to run this test suite.

This can be used to guide the development of the Khronos glTF plugin and as well as Blender if there are internal limitations to Blender's Principled 2.0 BSDF implementation.

I am willing to fund this on behalf of Threekit.

#### Live Demo

No live demo currently.

### Version

No relevant version.

### Browser Affected

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### OS

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### AR

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