A SpotLight emit light from a point in a specific direction in a cone volume.
SpotLight has a target that is always represented in words coordinates, and can be moved to change where the light is pointing at.
Based on THREE.SpotLight documentation for the object can be found at https://threejs.org/docs/index.html#Reference/Lights/SpotLight
SpotLight looks to the target object coordinates.
The target object should always be at the scene root.
Serialize SpotLight data to JSON.
Update light shadow map atributtes at runtime.