Alerting: Get grafana-managed alert rule by UID (#86845)

* Add auth checks and test

* Check user is authorized to view rule and add tests

* Change naming

* Update Swagger params

* Update auth test and swagger gen

* Update swagger gen

* Change response to GettableExtendedRuleNode

* openapi3-gen

* Update tests with refactors models pkg

pkg/services/ngalert/api/authorization_test.go

@@ -40,7 +40,7 @@ func TestAuthorize(t *testing.T) {
 		}
 		paths[p] = methods
 	}
-	require.Len(t, paths, 58)
+	require.Len(t, paths, 59)
 
 	ac := acmock.New()
 	api := &API{AccessControl: ac}