Shader used for deferred reflection probes.
When using deferred shading, reflection probes are rendered in "deferred" way by default.
All deferred objects in the Scene get per-pixel reflection probes that are calculated using this shader.
When setting deferred reflections shader to "disabled" (BuiltinShaderMode.Disabled), reflection probes are done in
per-object way, similar to how forward rendering computes them.
Additional resources: GraphicsSettings.SetShaderMode, BuiltinShaderMode, Graphics Settings.