### 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)

_THREAD_SAFE_METHOD_
	ERR_FAIL_COND_V(!windows.has(p_window), -1);
	EnumScreenData data = { 0, 0, MonitorFromWindow(windows[p_window].hWnd, MONITOR_DEFAULTTONEAREST) };
	EnumDisplayMonitors(nullptr, nullptr, _MonitorEnumProcScreen, (LPARAM)&data);
	return data.screen;
}
void DisplayServerWindows::window_set_current_screen(int p_screen, WindowID p_window) {
	_THREAD_SAFE_METHOD_
	ERR_FAIL_COND(!windows.has(p_window));
	ERR_FAIL_INDEX(p_screen, get_screen_count());
	if (window_get_current_screen(p_window) == p_screen) {
		return;
	}
	const WindowData &wd = windows[p_window];
	if (wd.fullscreen) {
		Point2 pos = screen_get_position(p_screen) + _get_screens_origin();
		Size2 size = screen_get_size(p_screen);
		MoveWindow(wd.hWnd, pos.x, pos.y, size.width, size.height, TRUE);
	} else {
		Rect2i srect = screen_get_usable_rect(p_screen);
		Point2i wpos = window_get_position(p_window) - screen_get_position(window_get_current_screen(p_window));
		Size2i wsize = window_get_size(p_window);
		wpos += srect.position;
		wpos.x = CLAMP(wpos.x, srect.position.x, srect.position.x + srect.size.width - wsize.width / 3);
		wpos.y = CLAMP(wpos.y, srect.position.y, srect.position.y + srect.size.height - wsize.height / 3);
		window_set_position(wpos, p_window);
	}
}
Point2i DisplayServerWindows::window_get_position(WindowID p_window) const {