[4.x]: Add event to allow modifying of query for the add line item table on the order edit page

[nfourtythree]

What happened?

Description

When trying to add a line item on the order edit page it could be useful for developers to hook into the retrieval of the list of purchasables.

Modifying that query to potential prevent certain purchasables from being shown.

Craft CMS version

4.x

Craft Commerce version

4.x