Closes #8550: Implement ASN ranges (#11835)

* Move ASN to a separate module

* Move ASNField from dcim to ipam

* Introduce ASNRange model

* Add relationship from ASN to ASNRange

* Add an available-asns API endpoint

* Add RIR assignment for ASNRange

* Add standard tests

* Move child ASNs to a tabbed view

* Remove FK on ASN to ASNRange

* Add tests for provisioning available ASNs

* Add docs for ASNRange

netbox/ipam/search.py

@@ -22,6 +22,14 @@ class ASNIndex(SearchIndex):
     )
 
 
+@register_search
+class ASNRangeIndex(SearchIndex):
+    model = models.ASNRange
+    fields = (
+        ('description', 500),
+    )
+
+
 @register_search
 class FHRPGroupIndex(SearchIndex):
     model = models.FHRPGroup