Introduce k8s like state to easegress controllers

[suchen-sci]

Is your feature request related to a problem? Please describe.
Providing more detailed and Kubernetes-like states to Easegress controllers.

Describe the solution you'd like
Introduce the following states to easegress controllers, accessible via egctl commands:

Pending: Indicates that a controller has been created but is not yet active or is in the process of initialization.
Running: Reflects that the controller is operating as expected and carrying out its tasks.
Failed: Signifies that an error has occurred within the controller, necessitating investigation or action.

When Failed, controllers should provide an error message for user to find problem (save time for checking log).

By implementing these states, users can gain more insight and easily identify potential issues. This proposal is open for further discussion and refinement to ensure alignment with easegress's existing architecture and the specific needs of its users.

[xxx7xxxx]

@suchen-sci Do you think we should implement this enhancement currently?