windows: Fix the event loop to wake on accessibility requests

[mwcampbell]

Fixes #4055.

It turns out this is easy to test even though AccessKit doesn't yet support winit master. If you run the window example on Windows with the NVDA screen reader running without this fix, NVDA doesn't read the window title, or reads it with a severe delay. With this fix, it reads the window title immediately as expected, even though the application doesn't implement accessibility.

• Tested on all platforms changed
• Added an entry to the changelog module if knowledge of this change could be valuable to users
• Updated documentation to reflect any user-facing changes, including notes of platform-specific behavior
• Created or updated an example program if it would help users understand this functionality

[kchibisov]

From what I've seen on how options work in docs, the new one just adds SEND_MESSAGE, which I guess is what is used by 3rd party software to communicate stuff, so it's just broader version of what we've used before, thus should be fine.

[mwcampbell]

Yes, QS_ALLINPUT is a superset of QS_ALLEVENTS, so it just wakes on more types of messages.

[kchibisov]

Thanks, I'll wait for a couple of days and then make a new release if it's fine with you. It's holidays for the majority, so shouldn't really matter.

If you need release asap I can cut it though.

[mwcampbell]

I don't need a release for anything I'm doing. I just hope that nobody upgrades winit and breaks their app's accessibility in the meantime.