Update Buyer Code to only be editable from Vendor File Maintenance.
Updates the process in Vendor Maintenance to assign the buyer code to all primary vendor items in ARINVT01. This means Buyer Code assignments made in Vendor Maintenance will populate over to the Purchasing tab of Inventory Maintenance.
Also makes the Buyer Code on the Purchasing tab of Inventory Maintenance read-only, which prevents Buyers from going out of sync between Vendor and Inventory Maintenance.