[cwctl] allow overriding config settings from the command line (closes #5557656)
eg.
cubicweb-ctl start -p port:8082 myapp
to overload the port parameter defined in the all-in-one.conf file.
Upstream Author:
%(author)s <%(author-email)s>
Copyright:
Copyright (c) %(year)s %(author)s.
%(author-web-site)s -- mailto:%(author-email)s