feat/dynamic-watches

[roivaz]

Adds the ability to watch the controller owned resources automatically and dynamically once the controller is already started.
The idea is that the type tracker, that was already implemented and was being used for the resource pruner, now also sets up a new watch each time it sees a new resource type (GVK) being managed by the controller.

Pros:

• Only watch for the APIs that the controller is actually using. Useful if the controller has optional dependencies on other APIs as avoids the requirement of always installing them in the cluster

Cons:

• controller-runtime does not provide currently a way of removing a watch from a controller. In the case an API is no longer of interest to the controller it will continue watching it. The workaround is to recreate the controller pod. There's work in progress to provide this capability in controller-runtime: ⚠ Support shutdown watches dynamically (v2) kubernetes-sigs/controller-runtime#2159.

I have also added some missing documentation and fixed several misspells.

/kind feature
/kind documentation
/assign
/priority important-soon

[3scale-robot]

LGTM label has been added.

Git tree hash: de1539935ee9b9b11037e41ea8ce75d9715df26a

[roivaz]

/approve

[3scale-robot]

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