[Epic]: Model Editor

[dinomut1]

Summary

• [x] support non entity object3d in editor hierarchy : #6636

Expanded Inspector + Editor

• [ ] add paginated list component
• [ ] click raycast to select object3ds when model is already selected
• [ ] transform inspector for object3ds
• [x] geometry and material inspector for meshes: #6777
• [ ] instancing transforms (+ additional buffer attriibutes) inspector for instanced meshes.
• [ ] add toggle setting to include exploded object3d
• [ ] better nested json editor
• [ ] batch metadata editor tool

GLTF exporter

Implement extension serializers

• [ ] DRACO compression
• [ ] meshopt compression
• [x] meshgpu_instancing: #6754
• [x] khr_texturebasisu: #6754

Serverside serialization via feathers

• [x] add 'save model' button to model editor: #6754