Support for Variants in glTF

[thomlucc]

To manage the various possible configurations of a product, the Configuration working group of the 3D Commerce is planning to move the "FB_material_variants" to an EXT extension and potentially to a KHR extension.

-> Link to glTF issue to provide feedback if any: KhronosGroup/glTF#1681

[deltakosh]

@bghgary Do you recommend implementing it now?

[bghgary]

I lean towards no unless we have partners/scenarios that we can support.

[thomlucc]

Mike Bond from Adobe is working on it and should submit a PR (discussed in the Metada working group )

[sebavan]

PR has been done and merged