Instead of storing the event handler within the AppState, and extracting
it our every time we need it, we now use the same event handling
implementation as for macOS that ensures we don't re-entrantly call the
event handler, and that we un-register the handler again after we're
done using it (`UIApplicationMain` won't return, but may still unwind,
so this is very important for panic safety).
This allows the user to override the application delegate themselves,
which opens several doors for customization that were previously closed.
To do this, we use notifications instead of top-level application delegate
methods.
One effect of not providing an application delegate on iOS is that we no
longer act as-if the application successfully open all URLs there.
This is a breaking change, although unlikely to matter in practice, since the
return value of `application:didFinishLaunchingWithOptions:` is seldom used by
the system (and is likely the preferred behaviour anyhow).
Move iOS and macOS implementations to a shared folder called `apple`, to allow
us to reduce the code-duplication between these platforms in the future.
The folder structure is now:
- `src/platform_impl/apple/`
- `appkit/`
- `uikit/`
- `example_shared_file.rs`
- `mod.rs`
* Add preliminary support for tvOS, watchOS and visionOS
* Reduce duplication in Cargo.toml when specifying dependencies
