Bulk generate support for parts

[wolflu05]

Allow to bulk create also parts including parameters, image, notes, ...

TODO

• [x] refactor FieldDefinition out of BulkGenerator module => apply model_instance in post init
• [x] add select helper for model type fields to UI
• [x] add select helper for image fields to UI (images from remote url)
• [x] add list/object field type to backend and UI (required for parameters field)
• [x] load default parameters for category
• [x] add attachment field (download from url missing - download before creating parts by extending create_objects so download happens outside of db transaction)
• [x] add stock field
• [x] add supplier field
• [x] add manufacturer field
• [x] use creation_user
• [x] add model type field to PartCategory
• [x] make get_custom_panels method more generic
• [x] add required check to list and dict if not present in generate instead of always return None
• [x] Add download image from url function
• [x] add preview for nested/native (model, image, ...) fields in preview table
• [x] Undefined description render for child if key is only used in parent
• [x] Template detection for empty bools does not work
• [x] validate models if object with that pk and limit options exist in cast_func which can be used as a validator too
• [x] validate select field option on server, important for stock status
• [x] use select field for stock status
• [x] docs -> moved to other PR
  • [x] new generate fields with native/template selection
  • [x] new generate dialog with inputs
  • [x] add section describing where to find the panels
  • [x] context that is available
• [x] tests
• [x] https://github.com/inventree/InvenTree/pull/5480

resolves #45

[github-actions[bot]]

Coverage Report

	Name	Stmts	Miss	Cover	Missing
inventree_bulk_plugin/BulkGenerator/BulkGenerator.py	163	0	100%
inventree_bulk_plugin/BulkGenerator/dimensions.py	66	0	100%
inventree_bulk_plugin/BulkGenerator/generators/gen_alpha.py	36	0	100%
inventree_bulk_plugin/BulkGenerator/generators/gen_numeric.py	14	0	100%
inventree_bulk_plugin/BulkGenerator/generators/generator.py	33	0	100%
inventree_bulk_plugin/BulkGenerator/template.py	10	0	100%
inventree_bulk_plugin/BulkGenerator/utils.py	19	0	100%
inventree_bulk_plugin/BulkGenerator/validations.py	53	0	100%
inventree_bulk_plugin/InvenTreeBulkPlugin.py	47	0	100%
inventree_bulk_plugin/api.py	70	0	100%
inventree_bulk_plugin/bulkcreate_objects.py	273	0	100%
inventree_bulk_plugin/migrations/0001_initial.py	6	0	100%
inventree_bulk_plugin/models.py	21	0	100%
inventree_bulk_plugin/serializers.py	52	0	100%
inventree_bulk_plugin/version.py	1	0	100%
TOTAL	864	0	100%