### Godot version

v4.0.beta17.mono.official [c40020513]

### System information

Windows 11 22H2

### Issue description

If a focused subwindow is destroyed, DisplayServerWindows may still attempt to send mouse motion events to that window, because `last_focused_window` isn't updated until another window is focused.

```
ERROR: Condition "!windows.has(p_window)" is true. Returning: Point2i()
   at: window_get_position (platform/windows/display_server_windows.cpp:999)
```

### Steps to reproduce

Run the MRP, click some non-Godot application window to focus it, then click the "CLOSE" button in the secondary window. This destroys the window without re-focusing the main window, so hovering the mouse over the main window will produce the error message above.

### Minimal reproduction project

[native_windows_hover.zip](https://github.com/godotengine/godot/files/10573386/native_windows_hover.zip)

if (!wd.event_callback.is_null()) {
		Variant event = int(p_event);
		Variant *eventp = &event;
		Variant ret;
		Callable::CallError ce;
		wd.event_callback.callp((const Variant **)&eventp, 1, ret, ce);
	}
}
void DisplayServerWindows::_dispatch_input_events(const Ref<InputEvent> &p_event) {
	static_cast<DisplayServerWindows *>(get_singleton())->_dispatch_input_event(p_event);
}
void DisplayServerWindows::_dispatch_input_event(const Ref<InputEvent> &p_event) {
	_THREAD_SAFE_METHOD_
	if (in_dispatch_input_event) {
		return;
	}
	in_dispatch_input_event = true;
	Variant ev = p_event;
	Variant *evp = &ev;
	Variant ret;
	Callable::CallError ce;
	{
		List<WindowID>::Element *E = popup_list.back();
		if (E && Object::cast_to<InputEventKey>(*p_event)) {
			
			if (windows.has(E->get())) {