Parameter types (#4935)

* Add fields to PartParameterTemplateModel

- checkbox: Is the field a 'checkbox'
- choices: List of valid options

* Update javascript

* Adds unit test for PartParameterTemplate

- Checkbox cannot have units
- Checkbox cannot have choices
- Choices must be unique

* Improve API filtering

- Add "has_choices" filter
- Add "has_units" filter

* Prune dead code

* Update js functions for creating / editing parameters

* Update part parameter form

- Rebuild the "data" field based on the selected template
- Supports "string" / "boolean" / "select"

* Adjust data input based on parameter type

- Choice displays available options
- Checkbox displays boolean switch
- Otherwise displays text input
- Adds more unit testing
- Updates to forms.js for improved functionality

* Calculate numeric value for boolean parameters

* Update docs

* Bump API version

InvenTree/part/serializers.py

@@ -216,6 +216,8 @@ class PartParameterTemplateSerializer(InvenTree.serializers.InvenTreeModelSerial
             'name',
             'units',
             'description',
+            'checkbox',
+            'choices',
         ]