Control build allocation of optional BOM items (#4090)

* Control build allocation of optional BOM items

- User can specify in form whether optional items are allocated
- Default = False

* Updated unit test

InvenTree/templates/js/translated/build.js

@@ -2422,6 +2422,9 @@ function autoAllocateStockToBuild(build_id, bom_items=[], options={}) {
         substitutes: {
             value: true,
         },
+        optional_items: {
+            value: false,
+        },
     };
 
     constructForm(`/api/build/${build_id}/auto-allocate/`, {