### Godot version

4.0 beta 10

### System information

Windows 10, Vulkan Renderer

### Issue description

In 2D scenes with sprites, when the sprite's `flip_h` and/or `flip_v` property is enabled, the normal map is flipped with the image, causing lighting to be reversed. While this does technically make sense, in a game where You have a bunch of sprites that flip and use normal maps, the only solution is to generate normal maps for both facing directions.
![image](https://user-images.githubusercontent.com/47702559/209426338-6257d66c-a965-4793-a7bb-5a635a136267.png)

Ultimately the fix is simple: Invert the red channel in normal maps on horizontally flipped sprites, and invert the green channel on vertically flipped sprites.

### Steps to reproduce

1) Create a Sprite2D
2) Add a Diffuse Texture and Normal Map 
3) Add a 2D Light to the scene
4) Enable `flip_h` and/or `flip_v` on the Sprite2D

### Minimal reproduction project

[Normal not flipped.zip](https://github.com/godotengine/godot/files/10298203/Normal.not.flipped.zip)

}
		if (!backbuffer_cleared && canvas_group_owner == nullptr && ci->canvas_group != nullptr && !backbuffer_copy) {
			texture_storage->render_target_clear_back_buffer(p_to_render_target, Rect2i(), Color(0, 0, 0, 0));
			backbuffer_cleared = true;
		}
		if (ci == canvas_group_owner) {
			if (update_skeletons) {
				mesh_storage->update_mesh_instances();
				update_skeletons = false;
			}
			_render_items(p_to_render_target, item_count, canvas_transform_inverse, p_light_list, starting_index, r_sdf_used, true);
			item_count = 0;
			if (ci->canvas_group->blur_mipmaps) {
				texture_storage->render_target_gen_back_buffer_mipmaps(p_to_render_target, ci->global_rect_cache);
			}
			canvas_group_owner = nullptr;
			
			backbuffer_cleared = false;
		}
		if (backbuffer_copy) {
			if (update_skeletons) {
				mesh_storage->update_mesh_instances();
				update_skeletons = false;
			}
			
			_render_items(p_to_render_target, item_count, canvas_transform_inverse, p_light_list, starting_index, r_sdf_used);
			item_count = 0;
			texture_storage->render_target_copy_to_back_buffer(p_to_render_target, back_buffer_rect, backbuffer_gen_mipmaps);
			backbuffer_copy = false;
			backbuffer_gen_mipmaps = false;