Can't add cancelled line item to invoice via internal Invoice Search

[Tiffany Little]

Tested on a 3.13 server as part of the July AIG meeting.

Using the invoice "Search" tab, if you select a line item with the status of "Cancelled" the "Add Lineitem(s) to Invoice" button is disabled. In Dojo, we were able to add any line item in any status to an invoice. We definitely want the ability to add line items in the "Cancelled" state to invoices, since this would include backordered items.

We also tested that from within a purchase order you are able to select a cancelled line item and either create a new invoice with it successfully, or you are also able to link it to an existing invoice.