Allow sorting of part table by unallocated_stock

InvenTree/part/api.py

@@ -1348,6 +1348,7 @@ class PartList(generics.ListCreateAPIView):
         'creation_date',
         'IPN',
         'in_stock',
+        'unallocated_stock',
         'category',
     ]
 

InvenTree/templates/js/translated/part.js

@@ -1384,7 +1384,7 @@ function loadPartTable(table, url, options={}) {
                         link = '?display=build-orders';
                     } else {
                         // There is no available stock
-                        value = `0<span class='badge badge-right rounded-pill bg-warning'>{% trans "Not available" %}</span>`;
+                        value = `0<span class='badge badge-right rounded-pill bg-warning'>{% trans "No stock available" %}</span>`;
                     }
                 }
             } else {