Align Scene::write_to_world_with to match DynamicScene::write_to_world_with

[dmyyy]

Objective

Fixes a regression in previously merged but then reverted pr that aligns lower-level Scene API with that in DynamicScene. Please look at the original pr for more details.

The problem was spawn_sync_internal is used in spawn_queued_scenes. Since instance creation was moved up a level we need to make sure we add a specific instance to SceneSpawner::spawned_instances when using spawn_sync_internal (just like we do for DynamicScene).

Please look at the last commit when reviewing.

Testing

alien_cake_addict and deferred_rendering examples look as expected.

Changelog

Changed Scene::write_to_world_with to take entity_map as an argument and no longer return an InstanceInfo

Migration Guide

Scene::write_to_world_with no longer returns an InstanceInfo.

Before

scene.write_to_world_with(world, &registry)

After

let mut entity_map = EntityHashMap::default();
scene.write_to_world_with(world, &mut entity_map, &registry)

[dmyyy]

@alice-i-cecile Anything I can do on my end to move this pr along?

[alice-i-cecile]

Can you swap this to a more descriptive title and then post about this in #scenes-dev please?

[dmyyy]

@NthTensor You approved the last version - do you have a chance to take a look at this updated one?

[MrGVSV]

I'm not too familiar with this part of the scene stuff but I think the change makes sense. It also seems to be in line with the call to Self::spawn_dynamic_internal a few lines up.

The alien_cake_addict example also seems to work properly again.

[MrGVSV]

@dmyyy I'd also recommend updating your PR description as parts of it are from #13714 and don't really have to do with this fix

Never mind, I didn't realize that PR was reverted and this is re-applying those commits.

[dmyyy]

@dmyyy I'd also recommend updating your PR description as parts of it are from #13714 and don't really have to do with this fix

Never mind, I didn't realize that PR was reverted and this is re-applying those commits.

The description is a little bit confusing - I updated the wording a little