(sub-)packages outside of core (cli) should not need to know about confs and args

That would help to have a more modular design and use other (sub)packages and (sub)modules without the need of creating ConfigParser and ArgumentParser objects. It also would help to simplify tests configurations.

Additionally, a program should take into account in this order:

• cli arguments
• environment variables
• user configuration files
• system configuration files
• program defaults

That is currently almost match. but it would be better if they all can be took into account in a simpler way.

This is not for MVP, but creating the ticket cause i'm creating new code taking this into account, and would be nice to change at some point.

Some tickets, as legacy/trac#27358 (moved), happen because of this.