### 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_
	ERR_FAIL_COND(!windows.has(p_window));
	WindowData &wd = windows[p_window];
	if (wd.fullscreen || wd.maximized) {
		return;
	}
	Point2i offset = _get_screens_origin();
	RECT rc;
	rc.left = p_position.x + offset.x;
	rc.right = p_position.x + wd.width + offset.x;
	rc.bottom = p_position.y + wd.height + offset.y;
	rc.top = p_position.y + offset.y;
	const DWORD style = GetWindowLongPtr(wd.hWnd, GWL_STYLE);
	const DWORD exStyle = GetWindowLongPtr(wd.hWnd, GWL_EXSTYLE);
	AdjustWindowRectEx(&rc, style, false, exStyle);
	MoveWindow(wd.hWnd, rc.left, rc.top, rc.right - rc.left, rc.bottom - rc.top, TRUE);
	wd.last_pos = p_position;
	_update_real_mouse_position(p_window);
}
void DisplayServerWindows::window_set_exclusive(WindowID p_window, bool p_exclusive) {