Provide a way to apply a global Override for Materials (Clay Mode like Vantage)

Right now, Envision doesn’t let you turn all materials into a gray, clay‑like look automatically.

In Chaos Vantage, there is a Clay Mode in the Material tab that lets you do this for the whole scene. You can choose the clay color, and still keep or turn off things like reflections, refractions, bump, opacity, self‑illumination, and even outline edges.

This would be super useful in Envision because:

• You could quickly make simple “white model” or concept style images.

• It helps everyone focus on shapes and lighting, not fancy textures.

• It speeds up work and presentations, especially when you just want to show design without distraction.

Add a full-scene Clay Mode like Vantage has. Let the user:

• Pick a gray or white override color.

• Turn on or off options such as reflections, refractions, bump, transparency, self-illumination, and edge outlines.