Rudder

See ticket #4917 for context.

This ticket aims to clean up some nasty complexity in update.cf:
- Tools copy was duplicated for windows (${g.rudder_sbin} directory) and !windows (${g.rudder_tools} directory) but ${g.rudder_tools} is set to (${g.rudder_sbin} on windows anyway, thus duplicating the exception
- Several class expressions were duplicated where promises could be regrouped
- A unused body was removed