Expose WindowDestroyed events

[arendjr]

Objective

I'm creating an iOS game and had to find a way to persist game state when the application is terminated. This required listening to the applicationWillTerminate() method, but I cannot do so myself anymore since winit already set up a delegate to listen for it, and there can be only one delegate.

So I had to move up the stack and try to respond to one of the events from winit instead. It appears winit fires two events that could serve my purpose: WindowEvent::Destroyed and Event::LoopDestroyed. It seemed to me the former might be slightly more generally useful, and I also found a past discussion that suggested it would be appropriate for Bevy to have a WindowDestroyed event: #5589 (comment)

Solution

• I've added the WindowDestroyed event, which fires when winit fires WindowEvent::Destroyed.

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Changelog

Added

• Introduced a new WindowDestroyed event type. It is used to indicate a window has been destroyed by the windowing system.

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[mockersf]

thanks for the contribution! Could you run cargo fmt on your PR?

[arendjr]

Hm, I did, but it didn't report any changes. But I've added the semicolon the CI was complaining about.

[Aceeri]

This is technically accomplishable with RemovedComponents I believe, but being consistent with the other events is helpful