`NcActionButton` should not leave uneeded space for icon if not provided

[nfebe]

First mentioned in : https://github.com/nextcloud/server/issues/41651

[ShGKme]

Makes sense, but only if all the action buttons don't have an icon. If only some actions don't have an icon, they should still have the space to be inline with other buttons, as it works in desktop menus.