Refactor 'pkg/kudoctl/util/kudo' into a cleaned-up package under 'pkg'

[nfnt]

What would you like to be added:
The pkg/kudoctl/util/kudo package provides functions to interface with the v1alpha1 clientset. Most functions wrap function arguments and translate types, but there's also functions to, e.g., install a package. As this can be considered a higher-level wrapping of KUDO API functions, these functions shouldn't live under a util folder. Furthermore, some cleaning up is necessary, some function names can be misleading and some function could be split up into smaller functions.

Why is this needed:
Better separation of concerns, clearer interface to clientset.