Add "Pacakge titles" accordion to package POL view

Purpose:  Rename the Linked instances accordion to "Package titles" accordion for the Package POL view. Allow users to add titles for receiving from this view so they don't need to leave the order app to finish building the order.

User story statement(s):

As an ordering librarian
I want to be able to add title information to my package POL from the orders app
so that I don't need to navigate to receiving to complete my order details.

Scenarios:

1. Scenario:
   • Given I have created an order and added a package POL
   • When viewing the package POL
   • Then I see an accordion called "Package titles" under the Item details accordion
2. Scenario:
   • Given I have created an order and added a package POL
   • When viewing the package POL
   • Then "Linked instances" accordion is replaced by the "Package titles" accordion