RFC - Implement Failed Job Admin

It might be nice to implement a job admin panel that lists all failed jobs. This could be done by having custom middleware/listeners that push the failed jobs into a database table, and then a basic page to view said jobs. We would also need a migration for creating that table, and ideally this would be something a user could generate for use with their app vs coming built-into the queue plugin.

I think @dereuromark has an example here, though in his case it also allows viewing more info about all jobs since they are all queued to the database.

In the future, we might even be able to expose other functionality/metrics in such an admin - this might involve work upstream to get the proper interfaces exposed - but I think starting here would be good enough :)

まず、参照されている dereuromark/cakephp-queue のドキュメントと docs/admin-backend の例を読み、そのアプローチをこのプラグインのキューインターフェースと比較します。失敗したジョブの保存、migration、ユーザーが生成する admin ページを含む最小限の最初のマイルストーンを定義します。実装前に、何を「done」とするかについて合意しておく必要があります。