windows: Use of MsgWaitForMultipleObjects breaks accessibility

[mwcampbell]

Accessibility on Windows is severely broken. The assistive technology (e.g. screen reader) can't consistently obtain UI Automation objects from the window, which means that basically nothing works.

Because the MsgWaitForMultipleObjects call uses QS_ALLEVENTS, which doesn't include QS_SENDMESSAGE, the event loop isn't awakened for blocking accessibility messages like WM_GETOBJECT. This was introduced by #3950, which was backported to winit v0.30.x and recently released in v0.30.6 and v0.30.7.

[kchibisov]

cc @AngelicosPhosphoros

[kchibisov]

I'd note that without it waiting doesn't really work at all, so we should find a way to have both working, otherwise users won't have a way to basically use anything on windows related to timers.