[wsgi] add the simplest possible wsgi (debug) server This server is able to: * serve on a given port using the stdlib SimpleHTTPServer * run looping tasks Closes #3005509.

usr/bin/cubicweb-ctl usr/bin/
usr/lib/PY_VERSION/*-packages/cubicweb/cwctl.py
../cubicweb-ctl.bash_completion etc/bash_completion.d/cubicweb-ctl