Shadow error with alphaCutOff

When changing alphaCutOff of the material, the shadow don’t change

The property to use alpha from the albedo texture of the PBR material is useAlphaFromAlbedoTexture, not hasAlpha.

Also, currently the shadow generator is using a fixed 0.4 value for the alphaCutOff value. This PR will fix that and use the one from the material:

Here’s the fixed PG that will work once the PR is merged: