[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.
usr/lib/PY_VERSION/*-packages/cubicweb/server/
usr/lib/PY_VERSION/*-packages/cubicweb/hooks/
usr/lib/PY_VERSION/*-packages/cubicweb/sobjects/
usr/lib/PY_VERSION/*-packages/cubicweb/schemas/
usr/share/cubicweb/migration/