[Epic] Load GLTF straight into the ECS

[HexaField]

• Split up GLTFLoader into multiple typed files #10050
• Scene state snapshots store GLTF documents instead of entity json
• Reimplement editor control functions with gltf-transform
• GLTF loader should create entity hierarchy instead of us parsing the threejs object hierarchy
• GLTF based SceneLoadingSystem to deserialize changes straight into the ECS
• Scene JSON format becomes deprecated/redundant