Change Stock Management service to be optional, not required by Requisition service

Currently Stock is Required by Requisition (per tickets above). We may change this so that Stock is optional. If Stock service is not installed, then Requisition service would not have the columns that connect to stock (opening balance, received quantity, losses & adjustments, consumed quantity, closing balance). Alternatively, those columns could switch to "reporting-only" columns that do not send data to Stock Management but still allow data capture on the requisition form. 

Needs Product Owner and Architect input. After that, needs tech design, Acceptance Criteria, and careful testing plan.