### 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)

switch (uMsg) {
		case WM_GETMINMAXINFO: {
			
			
			
		} break;
		case WM_NCCREATE: {
			
			
			CREATESTRUCTW *pCreate = (CREATESTRUCTW *)lParam;
			WindowData *pWindowData = reinterpret_cast<WindowData *>(pCreate->lpCreateParams);
			
			pWindowData->hWnd = hWnd;
		} break;
		default: {
			
			
			
			ERR_PRINT_ONCE(vformat("Unexpected window message 0x%x received for window we cannot recognize in our collection; sequence error.", uMsg));
		} break;
	}
	if (user_proc) {
		return CallWindowProcW(user_proc, hWnd, uMsg, wParam, lParam);
	}
	return DefWindowProcW(hWnd, uMsg, wParam, lParam);
}
LRESULT DisplayServerWindows::WndProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam) {