This PR implements the Lookdev (HDRI) Spheres overlay for EEVEE-Next. There are
also improvements for lookdev:
* Scene lighting (direct and indirect are) applied to the spheres.
* Shadow is applied to the spheres.
This is done by virtually placing the balls at the near clip plane of the camera/viewport.

Pull Request: https://projects.blender.org/blender/blender/pulls/115465