informer cache sync needs a timeout

[mars1024]

What would you like to be added:
A timeout should be introduced to stop waiting informer cache sync forever, even it will never succeed.

Why is this needed:
https://github.com/kubernetes-sigs/kubefed/blob/5b1f868c77383ada5c19e0f3aff1a5d6f2075941/pkg/controller/sync/controller.go#L206-L229

Now isSynced function will prevent reconciliations, but it only returns true or false, which means we will wait forever, even it may not succeed.

cc @zqzten

/kind feature

[zqzten]

/assign