feat: use fake client-set and informer add controller unittest.

[zjj2wry]

The controller now uses informer, list, clientset. For the controller test client-go provides fake-client and "k8s.io/client-go/testing" package to help test. Use them can test the logic of the controller worker is correct.

/cc @jlewi @ScorpioCPH @gaocegege

[gaocegege]

The test code is inspired by test in job controller in Kubernetes. And I do think we should use fake clientset instead of the normal clientset.

Thanks for the issue.

[stale]

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