Update assessfinancecharge.sql

Changes needed to fulfill Feature Request 23344 to enhance the information shown on the invcitem records for Finance Charge invoices.
Update itemsite.sql

Changes needed to add item number to Negative Quantity Average Cost error messages per Feature Request 21645.
Merge pull request #1824 from krauseo/master

Issues 21645 and 23344 - updates to assessfinancecharge.sql and itemsite.sql