### 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(!tts, TypedArray<Dictionary>());
	return tts->get_voices();
}
void DisplayServerWindows::tts_speak(const String &p_text, const String &p_voice, int p_volume, float p_pitch, float p_rate, int p_utterance_id, bool p_interrupt) {
	ERR_FAIL_COND(!tts);
	tts->speak(p_text, p_voice, p_volume, p_pitch, p_rate, p_utterance_id, p_interrupt);
}
void DisplayServerWindows::tts_pause() {
	ERR_FAIL_COND(!tts);
	tts->pause();
}
void DisplayServerWindows::tts_resume() {
	ERR_FAIL_COND(!tts);
	tts->resume();
}
void DisplayServerWindows::tts_stop() {
	ERR_FAIL_COND(!tts);
	tts->stop();
}
void DisplayServerWindows::mouse_set_mode(MouseMode p_mode) {
	_THREAD_SAFE_METHOD_
	if (mouse_mode == p_mode) {
		
		return;
	}
	mouse_mode = p_mode;
	_set_mouse_mode_impl(p_mode);
}
DisplayServer::MouseMode DisplayServerWindows::mouse_get_mode() const {