Ability to add to SLT appicable items and vendors

User is able to add to SLT only created PO which are sorted by Item, PO# or Vendor.

To create SLT with appicable items, user needs to do the next steps:

1. Create PO;
2. Open Shipment Load Tracking list -> Add New;
3. Click on Add to SLT -> Enter the required Item and Vendor -> Choose PO