### 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)

if (drop_events) {
		if (user_proc) {
			return CallWindowProcW(user_proc, hWnd, uMsg, wParam, lParam);
		} else {
			return DefWindowProcW(hWnd, uMsg, wParam, lParam);
		}
	}
	WindowID window_id = INVALID_WINDOW_ID;
	bool window_created = false;
	
	
	
	for (const KeyValue<WindowID, WindowData> &E : windows) {
		if (E.value.hWnd == hWnd) {
			window_id = E.key;
			window_created = true;
			break;
		}
	}
	
	
	
	if (!window_created) {
		
		return _handle_early_window_message(hWnd, uMsg, wParam, lParam);
	}
	
	switch (uMsg) {
		case WM_NCHITTEST: {
			if (windows[window_id].mpass) {