[FIX] purchase_analytic_plans: Purchase orders created with invoice poli...

...cy 'Based on incoming shipments' is not taking into account analytic distribution(which was fed at purchase order line) when it is invoiced. (Maintenance Case: 607577)

Steps to reproduce the issue:
1) Create a purchase order,
2) Add an order line and assign/create "Analytic Distribution",
3) Set "Invoicing Control" of the PO to "Based on incoming shipments",
4) Validate the PO, process the incoming shipment and create the invoice.

Current behavior: The "Analytic Distribution" in the created invoice is not set.

Expected behavior: The "Analytic Distribution" set in the order line should be set in it's respective invoice line.

This part is missing in the "purchase_analytic_plans" module, I have added it in this commit.