7025 circuit redundancy (#16945)

* 7025 CircuitRedundancyGroups

* 7025 CircuitRedundancyGroups api

* 7025 CircuitRedundancyGroups api

* 7025 CircuitRedundancyGroups tests

* 7025 CircuitRedundancyGroup -> CircuitGroup

* 7025 add tenancy

* 7025 linkify name

* 7025 missing file

* 7025 circuitgroupassignment

* 7025 base group assignment working

* 7025 assignments

* 7025 fix forms/tests for CircuitGroup

* 7025 fix api tests

* 7025 view tests

* 7025 CircuitGroupAssignment tests

* 7025 fix typo

* 7025 fix typo

* 7025 fix tests

* 7025 remove m2m

* 7025 add count to serializer

* 7025 fix test

* 7025 documentation

* 7025 review comments

* 7025 review comments

* 7025 add search index

* Make CircuitPriorityChoices extensible

* Add group assignment table to circuit view

* Misc cleanup

---------

Co-authored-by: Jeremy Stretch <jstretch@netboxlabs.com>

docs/models/circuits/circuitgroup.md

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+# Circuit Groups
+
+[Circuits](./circuit.md) can be arranged into administrative groups for organization. The assignment of a circuit to a group is optional.
+
+## Fields
+
+### Name
+
+A unique human-friendly name.
+
+### Slug
+
+A unique URL-friendly identifier. (This value can be used for filtering.)

docs/models/circuits/circuitgroupassignment.md

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+# Circuit Group Assignments
+
+Circuits can be assigned to [circuit groups](./circuitgroup.md) for correlation purposes. For instance, three circuits, each belonging to a different provider, may each be assigned to the same circuit group. Each assignment may optionally include a priority designation.
+
+## Fields
+
+### Group
+
+The [circuit group](./circuitgroup.md) being assigned.
+
+### Circuit
+
+The [circuit](./circuit.md) that is being assigned to the group.
+
+### Priority
+
+The circuit's operation priority relative to its peers within the group. The assignment of a priority is optional. Choices include:
+
+* Primary
+* Secondary
+* Tertiary
+* Inactive
+
+!!! tip
+    Additional priority choices may be defined by setting `CircuitGroupAssignment.priority` under the [`FIELD_CHOICES`](../../configuration/data-validation.md#field_choices) configuration parameter.