Make ExtractComponentPlugin etc. generic on AppLabel

[Zeophlite]

Objective

• Bevy's extraction process is implicitly for copying data from the main sub-app to the RenderApp sub-app
• Penultimate PR towards making the extract infra is reusable for non-rendering crates (see bevy_extract tracking #24483 )

e.g.

// Extract a component from the main subapp to the render subapp, and the audio subapp

#[derive(Component, Clone, Debug, ExtractComponent)]
#[extract_app(RenderApp, AudioApp)]
struct SomeComponent;

Solution

Followed by final PR in tracking issue is #22852 , which moves extraction to a new crate - as such, this PR retains "render" specific language where it was too awkward to change

Please review commit-by-commit

• 751031749f - Add Default to AppLabel's
• ff2fd56857 - Generalise SyncToRenderWorld = SyncToSubWorld<RenderApp> and RenderEntity = SubEntity<RenderApp>
• 8d7d5a4f70 - Generalise entity_sync_system to use AppLabel (ExtractPlugin specifies entity_sync_system::<RenderApp>)
• c7052bdd50 - Update ExtractInstance to be explicit for RenderApp . Update ExtractInstancesPlugin to be generic on AppLabel
• 1816340fae
  • Update ExtractComponentPlugin to be generic on L : AppLabel = RenderApp - in followup PR we will remove this default.
  • Same for ExtractResourcePlugin and SyncComponentPlugin.
  • Update SyncWorldPlugin to be generic on AppLabel.
  • Update ExtractPlugin to be generic on AppLabel.
  • Update RenderPlugin to specify ExtractPlugin<RenderApp>.
• fabe19de6e - Update SyncComponentPlugin to use an observer, rather than hook
• 899ee25caa - Dual extraction
• fdca1f24e9 - Support #[extract_app(AppA,AppB)] in derive(ExtractComponent)
• 2a68d73ba1 - Merge migration guides
• d318511cd0 - CI fixes

Simplified by #23377

Testing

• CI
• cargo run --example animated_mesh

[github-actions]

You added a new example but didn't add metadata for it. Please update the root Cargo.toml file.