[TW] Val'kyr Shadowguard

- Old hack for valkyr stun despawn
- Move Remove UNIT_FLAG_NOT_SELECTABLE to EVENT_MOVE_TO_DROP_POS  fix
teleport to edge (maybe)
- Get 2d distance and not 3d in EffectChargeDest
- Send target z posistion to GetFirstCollisionPosition and then
MovePositionToFirstCollision since they don't work in 3d space and
flying units just stay on the same z