Implement Hadron worker CR watch loop

[thedodd]

Implement the K8s CR watch loops for the various CRs. For each CR, it will be as simple as:

let clusters: Api<models::HadronCluster> = Api::all(self.client.clone());
let cluster_changes = watcher(clusters, ListParams::default());

Each change will then be handled by a specific function per CR type. Changes will cause updates to the metadata cache in the app, and will trigger spawning of controllers for Stream partitions, Pipeline partitions and other such objects.

Communication channels for spawned objects should then be passed along to the network controller to facilitate networking.

[thedodd]

Donel.