EU ETS - change portactivity control behaviour on veslink forms

To be able to correctly capture and reflect the ROB at port activities , the behavior of the control needs to be changed as by default it deletes all existing port activities and then only add what is entered in this control. right now, if we use this control on multiple forms then only the activities submitted from the last form stays in VIP and all other activities submitted by previous forms gets deleted. Fixing the behavior from delete, add to append/update will benefit everyone for correct calculation of Eu ETS.