Show soldier shields correctly on statues and logoff ghosts.

Currently both logoff ghosts and statues have issues with displaying soldier shields when they are on the back of a player, as neither object was ever updated to correctly handle this case. This pull request allow both objects to select the correct group to display based on whether the shield is on the player's back or not. Added a function in player.kod to query the shield for its hotspot as LookupPlayerShield doesn't check for shields on backs (as it's used for defensive stuff also).