### 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)

ERR_FAIL_COND_V(!windows.has(p_window), 0);
	switch (p_handle_type) {
		case DISPLAY_HANDLE: {
			return 0; 
		}
		case WINDOW_HANDLE: {
			return (int64_t)windows[p_window].hWnd;
		}
#if defined(GLES3_ENABLED)
		case WINDOW_VIEW: {
			if (gl_manager) {
				return (int64_t)gl_manager->get_hdc(p_window);
			}
			return 0;
		}
		case OPENGL_CONTEXT: {
			if (gl_manager) {
				return (int64_t)gl_manager->get_hglrc(p_window);
			}
			return 0;
		}
#endif
		default: {
			return 0;
		}
	}
}
void DisplayServerWindows::window_attach_instance_id(ObjectID p_instance, WindowID p_window) {