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/forms/fields/array.py

@@ -0,0 +1,24 @@
+from django import forms
+from django.contrib.postgres.forms import SimpleArrayField
+
+from ..utils import parse_numeric_range
+
+__all__ = (
+    'NumericArrayField',
+)
+
+
+class NumericArrayField(SimpleArrayField):
+
+    def clean(self, value):
+        if value and not self.to_python(value):
+            raise forms.ValidationError(f'Invalid list ({value}). '
+                                        f'Must be numeric and ranges must be in ascending order')
+        return super().clean(value)
+
+    def to_python(self, value):
+        if not value:
+            return []
+        if isinstance(value, str):
+            value = ','.join([str(n) for n in parse_numeric_range(value)])
+        return super().to_python(value)