Apply informer-operator design pattern to implement the drivers

[hainesc]

The informer-operator design pattern is popular in k8s, especially for the event driven component such as deploy-controller.

With a deep insight, the mapper is an event driven controller indeed. The only different from the deploy controller is the event source. Event of the former comes from the api server while event of the mapper comes from the change of disk file(mount configmap as a local file) and MQTT, I think it is worth to make the two event sources(Or anything that the event comes from) as an Informer implementation, so the driver developer can write their mapper as what they do in operator development, it is more friendly for them.

Thanks!