fix: item_code filter in item-wise sales-purchase register

[Nihantra-Patel]

Version 15

fixes: #41910

Before:

• Item code field is in the Sales Invoice Item or Purchase Invoice Item, is not a field of Sales Invoice or Purchase Invoice.

before_item-wise-sales_purchase_report.mp4

After:

• Also add the item code filter in the item-wise sales register.

after_item-wise-sales_purchase_report.mp4