Sales Order Allocation Improvements (#4556)

* Do not remove sales order allocations when returning an item against a return order

* Also do not clear allocations when returning manually

* stock item display tweaks

* Add extra column to sales order allocation table

* Improve methods for introspecting sales order allocations for stockitems

* Only display "active" sales order allocations on a stock item detail page

- All allocations are still visible in the allocation table

* Can't have available quantity if you're not available

tap's side of nose

InvenTree/order/models.py

@@ -1766,9 +1766,6 @@ class ReturnOrder(TotalPriceMixin, Order):
 
         stock_item = line.item
 
-        # Remove any allocations against the returned StockItem
-        stock_item.clearAllocations()
-
         deltas = {
             'status': StockStatus.QUARANTINED,
             'returnorder': self.pk,