Attach shipment legs loads

If a load has a committed tractor and/or trailer equipment type, the Load Build module will only allow shipment legs to be added to it if one of the following situations is true:

• Shipment leg does not have a corresponding equipment type specified
• Shipment leg has an equipment type specified and committed that matches the load's committed equipment type

If the load does not have an equipment type specified, the load's equipment type will be overwritten by the shipment leg's equipment type if this is committed.