For EventLoop, EventLoopBuilder, EventLoopProxy and by requiring it as
a supertrait of Window and ActiveEventLoop.
It is especially useful for user to be able to know that Window is Debug.
Requires getting permission from the user to get "detailed" support.
Also enables users to go fullscreen on specific monitors.
Exposes platform-specific orientation API.
Most functionality depends on browser support, currently only Chromium.
- Internal: Fix dropping `Notifier` without sending a result causing `Future`s to never complete. This should never happen anyway, but now we get a panic instead of nothing if we hit a bug.
- Internal: Remove a bunch of `unwrap()`s that aren't required when correctly using `MainThreadMarker`.
- `Window::canvas()` is now able to return a reference instead of an owned value.
Extracted from #3801.
