Proposal: stop using "namespace" classes

[dcermak]

Problem description

We are using quite a few "namespace only" classes like, e.g. the Privileges class:

kiwi/kiwi/privileges.py

Line 26 in bd442f6

class Privileges:

To be frankly honest, the class serves no purpose except to provide yet another namespace. It feels like a weird relic from C++/Java days where static only classes were a thing.

Given that we are taking the liberty to break things with kiwi-10, I would propose we stop using these and just make these free functions. Python has great support for namespaces, so this would make the code more pythonic. However, since this is a change without any real benefit and just because, I definitely don't insist on it.