Improvements for part creation API endpoint (#4281)

* Refactor javascript for creating a new part

* Simplify method of removing create fields from serializer

* Fix bug which resulted in multiple model instances being created

* remove custom code required on Part model

* Reorganize existing Part API test code

* Add child serializer for part duplication options

* Part duplication is now handled by the DRF serializer

- Improved validation options
- API is self-documenting (no more secret fields)
- More DRY

* Initial stock is now handled by the DRF serializer

* Adds child serializer for adding initial supplier data for a Part instance

* Create initial supplier and manufacturer parts as specified

* Adding unit tests

* Add unit tests for part duplication via API

* Bump API version

* Add javascript for automatically extracting info for nested fields

* Improvements for part creation form rendering

- Move to nested fields (using API metadata)
- Visual improvements
- Improve some field name / description values

* Properly format nested fields for sending to the server

* Handle error case for scrollIntoView

* Display errors for nested fields

* Fix bug for filling part category

* JS linting fixes

* Unit test fixes

* Fixes for unit tests

* Further fixes to unit tests

InvenTree/company/fixtures/company.yaml

@@ -46,3 +46,12 @@
     name: Another manufacturer
     description: They build things and sell it to us
     is_manufacturer: True
+
+- model: company.company
+  pk: 8
+  fields:
+    name: Customer only
+    description: Just a customer
+    is_customer: True
+    is_supplier: False
+    is_manufacturer: False

InvenTree/company/models.py

@@ -94,17 +94,6 @@ class Company(MetadataMixin, models.Model):
         ]
         verbose_name_plural = "Companies"
 
-    def __init__(self, *args, **kwargs):
-        """Custom initialization routine for the Company model.
-
-        Ensures that custom serializer fields (without matching model fields) are removed
-        """
-
-        # Remote image specified during creation via API
-        kwargs.pop('remote_image', None)
-
-        super().__init__(*args, **kwargs)
-
     name = models.CharField(max_length=100, blank=False,
                             help_text=_('Company name'),
                             verbose_name=_('Company name'))