[PATCH 2 of 3] configitems: use codemod script to register coreconfigitems

[Jun Wu]

Excerpts from Jun Wu's message of 2017-07-12 18:22:47 -0700:
> This is the result of running:
> 
>   contrib/codemod/codemod_configitems.py mercurial/**/*.py

This line should be:

  contrib/codemod/codemod_configitems.py {mercurial,hgext}/**/*.py

I have got it right in some local commits. But I have too many vim windows
when copy pasting so it eventually got lost.

(I should have sent this to Phabricator since in-place amends are much easier)