Gltf 2.0 spec says that every bone must have a direct/indirect parent, so a bone's parent might not necessarily be another bone which allows the skin to have several root bones. See one of Mixamo's downloaded skeletons for an example of this.
GltfImporter will already create the node hierarchy so this "indirect parent" connection will implicitly exist in the current workflow, so the changes in this PR just enable the usecases when the skin contains several bones with an indirect root parent
Gltf 2.0 spec says that every bone must have a direct/indirect parent, so a bone's parent might not necessarily be another bone which allows the skin to have several root bones. See one of Mixamo's downloaded skeletons for an example of this. GltfImporter will already create the node hierarchy so this "indirect parent" connection will implicitly exist in the current workflow, so the changes in this PR just enable the usecases when the skin contains several bones with an indirect root parent