Support image uploads in the "notes" markdown fields (#4615)

* Support image uploads in the "notes" markdown fields

- Implemented using the existing EasyMDE library
- Copy / paste support
- Drag / drop support

* Remove debug message

* Updated API version

* Better UX when saving notes

* Pin PIP version (for testing)

* Bug fixes

- Fix typo
- Use correct serializer type

* Add unit testing

* Update role permissions

* Typo fix

* Update migration file

* Adds a notes mixin class to be used for refactoring

* Refactor existing models with notes to use the new mixin

* Add helper function for finding all model types with a certain mixin

* Refactor barcode plugin to use new method

* Typo fix

* Add daily task to delete old / unused notes

* Bug fix for barcode refactoring

* Add unit testing for function

InvenTree/users/models.py

@@ -185,6 +185,7 @@ class RuleSet(models.Model):
         'common_webhookmessage',
         'common_notificationentry',
         'common_notificationmessage',
+        'common_notesimage',
         'users_owner',
 
         # Third-party tables