### 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)

case WM_MBUTTONDOWN: {
				MOUSEHOOKSTRUCT *ms = (MOUSEHOOKSTRUCT *)lParam;
				Point2i pos = Point2i(ms->pt.x, ms->pt.y) - _get_screens_origin();
				List<WindowID>::Element *C = nullptr;
				List<WindowID>::Element *E = popup_list.back();
				
				while (E) {
					
					Rect2i win_rect = Rect2i(window_get_position(E->get()), window_get_size(E->get()));
					
					Rect2i safe_rect = window_get_popup_safe_rect(E->get());
					if (win_rect.has_point(pos)) {
						break;
					} else if (safe_rect != Rect2i() && safe_rect.has_point(pos)) {
						break;
					} else {
						C = E;
						E = E->prev();
					}
				}
				if (C) {
					_send_window_event(windows[C->get()], DisplayServerWindows::WINDOW_EVENT_CLOSE_REQUEST);
					return 1;
				}
			} break;
		}
	}
	return ::CallNextHookEx(mouse_monitor, code, wParam, lParam);
}
LRESULT DisplayServerWindows::_handle_early_window_message(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam) {