Alerting: Provisioning API - Notification Policies (#46755)

* Base-line API for provisioning notification policies

* Wire API up, some simple tests

* Return provenance status through API

* Fix missing call

* Transactions

* Clarity in package dependencies

* Unify receivers in definitions

* Fix issue introduced by receiver change

* Drop unused internal test implementation

* FGAC hooks for provisioning routes

* Polish, swap names

* Asserting on number of exposed routes

* Don't bubble up updated object

* Integrate with new concurrency token feature in store

* Back out duplicated changes

* Remove redundant tests

* Regenerate and create unit tests for API layer

* Integration tests for auth

* Address linter errors

* Put route behind toggle

* Use alternative store API and fix feature toggle in tests

* Fixes, polish

* Fix whitespace

* Re-kick drone

* Rename services to provisioning

pkg/services/ngalert/api/authorization_test.go

@@ -47,7 +47,7 @@ func TestAuthorize(t *testing.T) {
 		}
 		paths[p] = methods
 	}
-	require.Len(t, paths, 29)
+	require.Len(t, paths, 30)
 
 	ac := acmock.New()
 	api := &API{AccessControl: ac}