### 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)


for (uint32_t i = 0; i < scene_state.shadow_passes.size(); i++) {
		
		SceneState::ShadowPass &shadow_pass = scene_state.shadow_passes[i];
		shadow_pass.rp_uniform_set = _setup_render_pass_uniform_set(RENDER_LIST_SECONDARY, nullptr, RID(), false, i);
	}
	RD::get_singleton()->draw_command_end_label();
}
void RenderForwardMobile::_render_shadow_end(uint32_t p_barrier) {
	RD::get_singleton()->draw_command_begin_label("Shadow Render");
	for (SceneState::ShadowPass &shadow_pass : scene_state.shadow_passes) {
		RenderListParameters render_list_parameters(render_list[RENDER_LIST_SECONDARY].elements.ptr() + shadow_pass.element_from, render_list[RENDER_LIST_SECONDARY].element_info.ptr() + shadow_pass.element_from, shadow_pass.element_count, shadow_pass.flip_cull, shadow_pass.pass_mode, shadow_pass.rp_uniform_set, 0, false, Vector2(), shadow_pass.lod_distance_multiplier, shadow_pass.screen_mesh_lod_threshold, 1, shadow_pass.element_from, RD::BARRIER_MASK_NO_BARRIER);
		_render_list_with_threads(&render_list_parameters, shadow_pass.framebuffer, RD::INITIAL_ACTION_DROP, RD::FINAL_ACTION_DISCARD, shadow_pass.initial_depth_action, shadow_pass.final_depth_action, Vector<Color>(), 1.0, 0, shadow_pass.rect);
	}
	if (p_barrier != RD::BARRIER_MASK_NO_BARRIER) {
		RD::get_singleton()->barrier(RD::BARRIER_MASK_FRAGMENT, p_barrier);
	}
	RD::get_singleton()->draw_command_end_label();
}
void RenderForwardMobile::_render_material(const Transform3D &p_cam_transform, const Projection &p_cam_projection, bool p_cam_orthogonal, const PagedArray<RenderGeometryInstance *> &p_instances, RID p_framebuffer, const Rect2i &p_region, float p_exposure_normalization) {
	RENDER_TIMESTAMP("Setup Rendering 3D Material");
	RD::get_singleton()->draw_command_begin_label("Render 3D Material");
	_update_render_base_uniform_set();
	RenderSceneDataRD scene_data;
	scene_data.cam_projection = p_cam_projection;
	scene_data.cam_transform = p_cam_transform;
	scene_data.view_projection[0] = p_cam_projection;
	scene_data.dual_paraboloid_side = 0;
	scene_data.material_uv2_mode = false;
	scene_data.opaque_prepass_threshold = 0.0f;