Closes: #9047 - Add Provider Accounts (#12057)

* #9047 - ProviderAccount

* #9047 - Move to new selector types

* #9047 - Re-introduce provider FK to Circuit model

* #9047 - Fix broken tests

* Misc cleanup

* Revert errant change

* Fix tests

* Update circuit filter form

---------

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

docs/models/circuits/circuit.md

@@ -8,6 +8,10 @@ A circuit represents a physical point-to-point data connection, typically used t
 
 The [provider](./provider.md) to which this circuit belongs.
 
+### Provider Account
+
+Circuits may optionally be assigned to a specific [provider account](./provideraccount.md).
+
 ### Circuit ID
 
 An identifier for this circuit. This must be unique to the assigned provider. (Circuits assigned to different providers may have the same circuit ID.)

docs/models/circuits/provider.md

@@ -16,10 +16,6 @@ A unique URL-friendly identifier. (This value can be used for filtering.)
 
 The [AS numbers](../ipam/asn.md) assigned to this provider (optional).
 
-### Account Number
-
-The administrative account identifier tied to this provider for your organization.
-
 ### Portal URL
 
 The URL for the provider's customer service portal.

docs/models/circuits/provideraccount.md

@@ -0,0 +1,17 @@
+# Provider Accounts
+
+This model can be used to represent individual accounts associated with a provider.
+
+## Fields
+
+### Provider
+
+The [provider](./provider.md) the account belongs to.
+
+### Name
+
+A human-friendly name, unique to the provider.
+
+### Account Number
+
+The administrative account identifier tied to this provider for your organization.