Allow BSS system to trigger service modification request.

By modification we mean: characteristic value change, status change (other ?).

Minimum could be to handle modification that can be managed in SO with a Delete Service and then Add service (this is a change up to nbi but remove/add down to nbi).

Optimal: get possibility to trigger service modification to SO

Note: This is not service order modification butt service modification on existing service instance in the inventory (new service order with action change)