Support for leader election

[calind]

Currently the manager won't do any kind of leader election. I think that the manager should implement of it so that you can run highly available controllers.

[DirectXMan12]

/kind feature

[JoelSpeed]

Does anyone know of any work already done on this? If not I'm going to look into this and try to raise a PR.

The first question I have about this is that the leader election will need a unique name per kubebuilder project. I assume this will have to come from a flag unless there is a unique identifier already, any ideas?

[zhujl1991]

@JoelSpeed When leader election is enabled, after I delete the deployment of my controller manager, the configmap won't be deleted automatically.