Use informer pattern instead of calling the kubernetes API

[ankitm123]

https://leftasexercise.com/2019/07/08/understanding-kubernetes-controllers-part-i-queues-and-the-core-controller-loop/
https://leftasexercise.com/2019/07/11/understanding-kubernetes-controllers-part-ii-object-stores-and-indexers/
https://leftasexercise.com/2019/07/15/understanding-kubernetes-controllers-part-iii-informers/
https://leftasexercise.com/2019/07/18/understanding-kubernetes-controllers-part-iv-putting-it-all-together/

This should help in reducing the load on the API server. This is already used by the visualizer and build controller.