### 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)

mbd->set_pressed(false);
				Input::get_singleton()->parse_input_event(mbd);
			}
		} break;
		case WM_WINDOWPOSCHANGED: {
			Rect2i window_client_rect;
			Rect2i window_rect;
			{
				RECT rect;
				GetClientRect(hWnd, &rect);
				ClientToScreen(hWnd, (POINT *)&rect.left);
				ClientToScreen(hWnd, (POINT *)&rect.right);
				window_client_rect = Rect2i(rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top);
				window_client_rect.position -= _get_screens_origin();
				RECT wrect;
				GetWindowRect(hWnd, &wrect);
				window_rect = Rect2i(wrect.left, wrect.top, wrect.right - wrect.left, wrect.bottom - wrect.top);
				window_rect.position -= _get_screens_origin();
			}
			WINDOWPOS *window_pos_params = (WINDOWPOS *)lParam;
			WindowData &window = windows[window_id];
			bool rect_changed = false;
			if (!(window_pos_params->flags & SWP_NOSIZE) || window_pos_params->flags & SWP_FRAMECHANGED) {
				int screen_id = window_get_current_screen(window_id);
				Size2i screen_size = screen_get_size(screen_id);
				Point2i screen_position = screen_get_position(screen_id);
				window.maximized = false;
				window.minimized = false;
				window.fullscreen = false;
				if (IsIconic(hWnd)) {