Account Invoice - Quantity Multiplier Update

This module extends the supplier info update wizard that appears on vendor bills. When you use that wizard to update a vendor's price information, you now also see the Quantity Multiplier field.

• In the wizard lines, a read-only column shows the current multiplier quantity, and an editable column lets you set a new multiplier quantity.
• The new multiplier quantity is required, so you must enter a value before confirming the update.
• When the wizard is applied, the multiplier quantity is written back to the supplier information record.
• The current multiplier column is hidden for lines that are not linked to an existing supplier information record.

The module touches the vendor bill line model (account.move.line) to prepare the wizard line values, and the wizard line model (wizard.update.invoice.supplierinfo.line) to store the current and new multiplier quantities. It also adds the two fields to the existing wizard form view. This is a glue module: it only works when both the supplier info update wizard and the product supplier info quantity multiplier features are installed.