Hide board switch from non-admins until end of statutory year

problem: requests for board changes are being sent before the end of the statutory year and newly added board members are directly visible for everyone to see, whilst a lot of local clubs keep their board secret until the actual ceremonial board switch.

solution: hide new board members until the end of the statutory year, so that their names and functions only become visible when they have officially taken up their duties. in an ideal situation, this would be linked to the option of clubs adding their own statutory years, so they can fully customise this for when they have scheduled the actual switch.