### Godot version

4.0 Stable

### System information

Ubuntu 22.04

### Issue description

Setting fog_affect_sky = 1 do not have the desired effect when using a Color sky mode. It works properly if we use a procedural sky or the forward+ renderer.

![Screenshot from 2023-03-03 16-50-53](https://user-images.githubusercontent.com/8985409/222870514-0195c4cb-bbca-4e9b-bb6a-6e2a568d2f7b.png)


### Steps to reproduce

Add a sky with a plain color mode like the Clear Color default option. Enable fog and set fog_affect_sky value to 1. Sky is still not affected by fog. 

### Minimal reproduction project
[mobile_fog_sky_bug.zip](https://github.com/godotengine/godot/files/10887265/mobile_fog_sky_bug.zip)


if (light_storage->light_omni_get_shadow_mode(base) == RS::LIGHT_OMNI_SHADOW_CUBE) {
				render_texture = light_storage->get_cubemap(shadow_size / 2);
				render_fb = light_storage->get_cubemap_fb(shadow_size / 2, p_pass);
				light_projection = light_storage->light_instance_get_shadow_camera(p_light, p_pass);
				light_transform = light_storage->light_instance_get_shadow_transform(p_light, p_pass);
				render_cubemap = true;
				finalize_cubemap = p_pass == 5;
				atlas_fb = light_storage->shadow_atlas_get_fb(p_shadow_atlas);
				atlas_size = shadow_atlas_size;
				if (p_pass == 0) {
					_render_shadow_begin();
				}
			} else {
				atlas_rect.position.x += 1;
				atlas_rect.position.y += 1;
				atlas_rect.size.x -= 2;
				atlas_rect.size.y -= 2;
				atlas_rect.position += p_pass * atlas_rect.size * dual_paraboloid_offset;
				light_projection = light_storage->light_instance_get_shadow_camera(p_light, 0);
				light_transform = light_storage->light_instance_get_shadow_transform(p_light, 0);
				using_dual_paraboloid = true;
				using_dual_paraboloid_flip = p_pass == 1;
				render_fb = light_storage->shadow_atlas_get_fb(p_shadow_atlas);
				flip_y = true;
			}
		} else if (light_storage->light_get_type(base) == RS::LIGHT_SPOT) {
			light_projection = light_storage->light_instance_get_shadow_camera(p_light, 0);
			light_transform = light_storage->light_instance_get_shadow_transform(p_light, 0);
			render_fb = light_storage->shadow_atlas_get_fb(p_shadow_atlas);
			flip_y = true;