GLB-parser: Add callbacks to handle all nodes of the scheme

Right now, in the container handler we can define the next callbacks according to different stages of asset loading: global, node, light, camera, animation, material, image, texture, buffer, bufferView. But it does not cover all nodes of the glTF scheme that has extension or extra, and one can't handle extension/extra for these nodes.

List of uncovered nodes that I just have found, but I'm not sure that there are all of them:

• Mesh.primitives
  • Documentation
  • Place in the code
  • Public extensions: KHR_lights_shadows, CESIUM_primitive_outline
• Mesh
  • Documentation
  • Place in the code
• Sampler
  • Documentation
  • Place in the code
• Accessor
  • Documentation: 1, 2
  • Place in the code
• Scene
  • Documentation
  • Place in the code
• Skin
  • Documentation
  • Place in the code