glTF exporter could assist with some glTF validation errors

[aiaustin]

Blender glTF exporter could assist with some of the glTF validation errors that might creep into models. Eg. pbrMetallicRoughness/baseColorFactor must be 0...1, but I see a validation error at 1.00016. I am not sure how such a value crept into the 3D model and materials. I can fix this, but maybe the exporter could assist in keeping the exported glTF valid.

[julienduroure]

Set as enhancement.
Currently, no check are done on colors, and Blender can handle values > 1.0 for them