Enable or disable control-word for static pseudowire in LDP VPLS instance and BGP VPLS mesh-group

Junos OS introduced the control-word and no-control-word options at the [edit routing-instances routing-instance-name protocols vpls mesh-group mesh-group-name neighbor address static] and [edit routing-instances routing-instance-name protocols vpls neighbor address static] hierarchy levels. The control-word configuration requests the other routers to insert a control word between the label stack and the MPLS payload.