### 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];
	wd.im_position = p_pos;
	HIMC himc = ImmGetContext(wd.hWnd);
	if (himc == (HIMC)0) {
		return;
	}
	COMPOSITIONFORM cps;
	cps.dwStyle = CFS_POINT;
	cps.ptCurrentPos.x = wd.im_position.x;
	cps.ptCurrentPos.y = wd.im_position.y;
	ImmSetCompositionWindow(himc, &cps);
	ImmReleaseContext(wd.hWnd, himc);
}
void DisplayServerWindows::cursor_set_shape(CursorShape p_shape) {