Currently, on X11, when activating a window that is not on the current desktop we allow this only if focus stealing protection is set to none.
If any focus stealing protection is set then activation is denied. That behavior is unintiutive to the user. When I e.g. click on a notification from a chat app I expect something to happen, regardless of focus stealing protection.
Remove the special handling of windows on different desktops and only apply the usual focus stealing prevention checks (based on timestamps etc). This also matches the behavior on Wayland.
To preserve the ability to not activate a window if it's on a different desktop add a third option to the activation behavior