✨ Static pod CustomPruningController

I am utilizing the static pod package (`library-go/pkg/operator/staticpod`) for a use case in which all pods require an init container for authz and authn. Due to this requirement, I need a CustomPruningController that, similar to the CustomInstallerController, accepts a function to changing the pruner pod before it is created. I have implemented a POC [here](https://github.com/JRPCF/library-go). This simple approach passes the function to the NewPruningController function. An alternative approach would be to refactor the PruningController function to implement the factory.controller similar to InstallerController. This approach would allow the function to be passed using the builder pattern similar to InstallerController but would require significant refactoring. Do the owners of this repo have a preference on the approach?