Eevee: World nodetree gpumaterial compatibility.

- Unify GPUMaterial creation (world/mesh).
- Support for multiple shader variations (not used for now).
- Convert GPUInputs to DRWUniforms to be used with the draw manager.
- Nodetree Update is not supported. The only way to refresh the shaders is to change render engine.
- Cleanup in GPUPass.
- Add new temporary Node Compatibility type. Compatibility types should be removed in the future.

source/blender/draw/engines/eevee/shaders/default_frag.glsl

@@ -3,9 +3,11 @@ uniform vec3 diffuse_col;
 uniform vec3 specular_col;
 uniform int hardness;
 
+out vec4 FragColor;
+
 void main()
 {
 	float roughness = 1.0 - float(hardness) / 511.0;
 	roughness *= roughness;
-	fragColor = vec4(eevee_surface_lit(worldNormal, diffuse_col, specular_col, roughness), 1.0);
+	FragColor = vec4(eevee_surface_lit(worldNormal, diffuse_col, specular_col, roughness), 1.0);
 }