Bug 34708: Add ability to modify orderline to increase quantity

Bug 34708: Add ability to modify orderline to increase quantity

This enhancement allows libraries to modify an existing orderline and increase the quantity in the order. The quantity is increased by adding more items to the order, through the usual Item for which is visible when adding or modifying an order.

To test:

1. Ensure you have a budget, fund, vendor etc. to use the Acquisitions module
2. Open a new basket. Make sure you do NOT check the 'orders are standing' option
3. Add an order to the basket using any method. Add an item or more to this orderline and save the order to the basket
4. Click Modify to edit the orderline
5. Notice the quantity text field. Try to directly change this number. You'll get an error pop-up and be redirected back to the basket.

6. Apply the patch, restart services, refresh the basket page

7. Click Modify to edit the orderline
8. Notice the item form and Items list table is visible with your existing item(s) for this order. There should be no Action buttons as actions can't be done on an existing item order.
9. Confirm you are able to add more items to the Items list and to the order by filling out the form and clicking 'Add item' as normal. Confirm the quantity increases accordingly.
10. Confirm the Edit and Delete buttons for newly added items work as expected
11. Save and confirm the quantity for the orderline has increased
12. Confirm this behaviour persists with the other methods of adding new orders to a basket

Sponsored-by: Pymble Ladies' College
Signed-off-by: Katariina Hanhisalo <katariina.hanhisalo@xamk.fi>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Perltidy
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>