### 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), Point2i());
	const WindowData &wd = windows[p_window];
	if (wd.minimized) {
		return wd.last_pos;
	}
	POINT point;
	point.x = 0;
	point.y = 0;
	ClientToScreen(wd.hWnd, &point);
	return Point2i(point.x, point.y) - _get_screens_origin();
}
Point2i DisplayServerWindows::window_get_position_with_decorations(WindowID p_window) const {