Add ace script to switch between bipod (high) and bipod (low) variants

[Viking181]

Add the above to maintain utility of CSW teams when 2-man teams are used.

Specifically variants "ace_csw_m3CarryTripod" to "ace_csw_m3CarryTripodLow" and "ace_csw_kordCarryTripod" to "ace_csw_kordCarryTripodLow"