Extension support

[alichraghi]

• KHR_animation_pointer
• KHR_draco_mesh_compression
• KHR_lights_punctual
• KHR_materials_anisotropy
• KHR_materials_clearcoat
• KHR_materials_dispersion
• KHR_materials_emissive_strength
• KHR_materials_ior
• KHR_materials_iridescence
• KHR_materials_sheen
• KHR_materials_specular
• KHR_materials_transmission
• KHR_materials_unlit
• KHR_materials_variants
• KHR_materials_volume
• KHR_mesh_quantization
• KHR_texture_basisu
• KHR_texture_transform
• KHR_xmp_json_ld
• EXT_mesh_gpu_instancing
• EXT_meshopt_compression
• EXT_texture_webp