Closes #12194: Add pre-defined custom field choices (#13219)

* Initial work on custom field choice sets

* Rename choices to extra_choices (prep for #12194)

* Remove CustomField.choices

* Add & update tests

* Clean up table columns

* Add order_alphanetically boolean for choice sets

* Introduce ArrayColumn for choice lists

* Show dependent custom fields on choice set view

* Update custom fields documentation

* Introduce ArrayWidget for more convenient editing of choices

* Incorporate PR feedback

* Misc cleanup

* Initial work on predefined choices for custom fields

* Misc cleanup

* Add IATA airport codes

* #13241: Add support for custom field choice labels

* Restore ArrayColumn

* Misc cleanup

* Change extra_choices back to a nested ArrayField to preserve choice ordering

* Hack to bypass GraphQL API test utility absent support for nested ArrayFields

netbox/utilities/forms/widgets/misc.py

@@ -2,6 +2,7 @@ from django import forms
 
 __all__ = (
     'ArrayWidget',
+    'ChoicesWidget',
     'ClearableFileInput',
     'MarkdownWidget',
     'NumberWithOptions',
@@ -54,3 +55,15 @@ class ArrayWidget(forms.Textarea):
         if value is None or not len(value):
             return None
         return '\n'.join(value)
+
+
+class ChoicesWidget(forms.Textarea):
+    """
+    Render each key-value pair of a dictionary on a new line within a textarea for easy editing.
+    """
+    def format_value(self, value):
+        if not value:
+            return None
+        if type(value) is list:
+            return '\n'.join([f'{k},{v}' for k, v in value])
+        return value