Allow all non?carrier -> non?carrier/self ka/tka dmg/force combos

Allow all non?carrier -> non?carrier/self ka/tka dmg/force combos

Implemented this similar to as described here https://gitlab.com/xonotic/xonotic-data.pk3dir/-/merge_requests/1431#note_2317419396, using a damage vector and force vector.
Currently the carrier -> carrier isn't very useful in ka/tka since there's only one ball, but this approach is consistent, and more balls may be allowed in future.
Consequently fixed up the comments.