Added GPU based cluster builder

Clustering is now GPU based, uses an implementation based on the Activision algorithm.

servers/rendering_server.h

@@ -856,7 +856,10 @@ public:
 		VIEWPORT_DEBUG_DRAW_SDFGI_PROBES,
 		VIEWPORT_DEBUG_DRAW_GI_BUFFER,
 		VIEWPORT_DEBUG_DRAW_DISABLE_LOD,
-
+		VIEWPORT_DEBUG_DRAW_CLUSTER_OMNI_LIGHTS,
+		VIEWPORT_DEBUG_DRAW_CLUSTER_SPOT_LIGHTS,
+		VIEWPORT_DEBUG_DRAW_CLUSTER_DECALS,
+		VIEWPORT_DEBUG_DRAW_CLUSTER_REFLECTION_PROBES,
 	};
 
 	virtual void viewport_set_debug_draw(RID p_viewport, ViewportDebugDraw p_draw) = 0;