message: refactor: use ember-concurrency-decorators for tasks in handbook engine
diff: import { computed } from '@ember/object';
  import Route from '@ember/routing/route';
  -import { task } from 'ember-concurrency';
  +import { task } from 'ember-concurrency-decorators';
  import ConfirmationMixin from 'ember-onbeforeunload/mixins/confirmation';
  import ValidatedModelFormController from './controller';
  -export default class ValidatedModelFormRoute extends Route.extend(ConfirmationMixin, {
  - modelTask: task(function *(this: ValidatedModelFormRoute) {
  +export default class ValidatedModelFormRoute extends Route.extend(ConfirmationMixin) {
  + @task
  + modelTask = task(function *(this: ValidatedModelFormRoute) {
  return yield this.store.findRecord('node', 'extng');
  - }),
  -}) {
  + });
  +
  model() {
  return {
  taskInstance: this.modelTask.perform(),
  