cubicweb #16133259 rework debian packaging [validation pending]

Now that we used setuptools unconditionally, our hand crafted debian/rules is non-functional (install steps fails and does not appear easy to fix) and is arguably non-maintainable at a reasonable cost.

I propose to switch to a simple build system, relying on modern dh-python/pybuild and to get rid of binary packages split (-server, -common, etc.) which, apart from dependency handling, does not add much value IMO. We may reintroduce some metapackage cubicweb-<FEATURE>-support for optional dependencies.

Also, we should rename our binary packages with a pythonX- prefix, to prepare for python3 packaging.

done in3.24.1
load left0.000
closed by#e8be49ecb522 [debian] Update debian packaging (closes #16133259)
patch[debian] Rework split of cubicweb-ctl package [applied][debian] Have a single python-cubicweb binary for the library [applied][debian] Update debian packaging (closes #16133259) [applied]