Combining the irradiance provided by DDGI with existing PBR implementations.

[roeas]

• To reuse the material shader, we define the Albedo, Normal, ORM, and Emissive texture slots in U_BaseSlot.sh and include it in Material.sh as well as SceneWorld.cpp. This also means that if you wish to include Material.sh in shader, the first 4 slots (0 - 3) will be occupied.