### 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)

_THREAD_SAFE_METHOD_
	drop_events = true;
	process_events();
	drop_events = false;
}
void DisplayServerWindows::release_rendering_thread() {
}
void DisplayServerWindows::make_rendering_thread() {
}
void DisplayServerWindows::swap_buffers() {
#if defined(GLES3_ENABLED)
	if (gl_manager) {
		gl_manager->swap_buffers();
	}
#endif
}
void DisplayServerWindows::set_native_icon(const String &p_filename) {