### 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.exclusive != p_exclusive) {
		wd.exclusive = p_exclusive;
		if (wd.transient_parent != INVALID_WINDOW_ID) {
			if (wd.exclusive) {
				WindowData &wd_parent = windows[wd.transient_parent];
				SetWindowLongPtr(wd.hWnd, GWLP_HWNDPARENT, (LONG_PTR)wd_parent.hWnd);
			} else {
				SetWindowLongPtr(wd.hWnd, GWLP_HWNDPARENT, (LONG_PTR) nullptr);
			}
		}
	}
}
void DisplayServerWindows::window_set_transient(WindowID p_window, WindowID p_parent) {