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/templates/notes_buttons.html

@@ -1,8 +1,8 @@
 {% load i18n %}
 
 <button type='button' id='edit-notes' title='{% trans "Edit" %}' class='btn btn-primary'>
-    <span class='fas fa-edit'></span> {% trans "Edit" %}
+    <span id='edit-icon' class='fas fa-edit'></span> {% trans "Edit" %}
 </button>
 <button type='button' id='save-notes' title='{% trans "Save" %}' class='btn btn-success' style='display: none;'>
-    <span class='fas fa-save'></span> {% trans "Save" %}
+    <span id='save-icon' class='fas fa-save'></span> {% trans "Save" %}
 </button>