[debian] Update debian packaging (closes #16133259)
- use dh_python, pybuild and debhelper>=9,
- refactor and simplify the debian/rules,
- rename binary packages (but cubicweb-ctl) to python-xxx
- remove daemon handling stuff (initscripts...) from cubicweb-ctl (one should
now use a standard WSGI delivery method),
usr/lib/python2*/*-packages/cubicweb/web
usr/lib/python2*/*-packages/cubicweb/wsgi
usr/share/cubicweb/cubes/shared/data
usr/share/cubicweb/cubes/shared/wdoc