Add socket binding data to scontrol node info

If GRES as associated with specific sockets, identify those sockets in the
    output of "scontrol show node". For example if all 4 GPUs on a node are
    all associated with socket zero, then "Gres=gpu:4(S:0)". If associated
    with sockets 0 and 1 then "Gres=gpu:4(S:0-1)". The information of which
    specific GPUs are associated with specific GPUs is not reported, but only
    available by parsing the gres.conf file.