setup a queue in rudr for events with error or need to wait and retry

[wonderflow]

We need to setup a queue, mainly for 2 reasons:

1. some error occurred and need to retry.
2. need to wait and retry.

The architecture is like this:

informer => queue => Instigator
             ↑↑          ||
             <<==requeue==V

[resouer]

xref: https://github.com/clux/kube-rs/issues/9

[wonderflow]

@technosophos do you think we need to write a library something like controller-runtime ? Or just use some rust way to solve this？

[technosophos]

For now, it would be fine to do it ourselves. Clux might be interested in adding something to his library if we wanted. Or if you would like to write your own Rust library and cargo it in, that would be fine with me! I'm sure many other people would benefit.