Closes #12246: General cleanup of utilities modules

* Clean up base modules

* Clean up forms modules

* Clean up templatetags modules

* Replace custom simplify_decimal filter with floatformat

* Misc cleanup

* Merge ReturnURLForm into ConfirmationForm

* Clean up import statements for utilities.forms

* Fix field class references in docs

netbox/utilities/urls.py

@@ -4,6 +4,10 @@ from django.views.generic import View
 
 from netbox.registry import registry
 
+__all__ = (
+    'get_model_urls',
+)
+
 
 def get_model_urls(app_label, model_name):
     """