Part units (#4854)

* Add validation to part units field

* Add "pack_units" field to the SupplierPart model

* Migrate old units to new units, and remove old field

* Table fix

* Fixture fix

* Update migration

* Improve "hook" for loading custom unit database

* Display part units column in part table

- Also allow ordering by part units
- Allow filtering to show parts which have defined units

* Adds data migration for converting units to valid values

* Add "pack_units_native" field to company.SupplierPart model

* Clean pack units when saving a SupplierPart

- Convert to native part units
- Handle empty units value
- Add unit tests

* Add background function to rebuild supplier parts when a part is saved

- Required to ensure that the "pack_size_native" is up to date

* Template updates

* Sort by native units first

* Bump API version

* Rename "pack_units" to "pack_quantity"

* Update migration file

- Allow reverse migration

* Fix for currency migration

- Handle case where no currencies are provided
- Handle case where base currency is not in provided options

* Adds unit test for data migration

* Add unit test for part.units data migration

- Check that units fields are updated correctly

* Add some extra "default units"

- each / piece
- dozen / hundred / thousand
- Add unit testing also

* Update references to "pack_size"

- Replace with "pack_quantity" or "pack_quantity_native" as appropriate

* Improvements based on unit testing

* catch error

* Docs updates

* Fixes for pricing tests

* Update unit tests for part migrations · 1b6b6d9d

* Bug fix for conversion code

* javascript updates

* JS formatting fix

InvenTree/part/test_api.py

@@ -2144,7 +2144,7 @@ class PartAPIAggregationTest(InvenTreeAPITestCase):
                     part=p,
                     supplier=supplier,
                     SKU=f"PNT-{color}-{pk_sz}L",
-                    pack_size=pk_sz,
+                    pack_quantity=str(pk_sz),
                 )
 
             self.assertEqual(p.supplier_parts.count(), 4)
@@ -2206,7 +2206,7 @@ class PartAPIAggregationTest(InvenTreeAPITestCase):
                         remaining = line_item.quantity - line_item.received
 
                         if remaining > 0:
-                            on_order += remaining * sp.pack_size
+                            on_order += sp.base_quantity(remaining)
 
             # The annotated quantity must be equal to the hand-calculated quantity
             self.assertEqual(on_order, item['ordering'])