[rset] Deprecate the 'encoded' argument to ResultSet.printable_rql()
It's hardly used at all, and when used inside CubicWeb, it's only set as
false. Better make sure that this function always returns a proper
unicode string and let the caller handle conversion on its own.
usr/lib/PY_VERSION/*-packages/cubicweb/web
usr/lib/PY_VERSION/*-packages/cubicweb/wsgi
usr/share/cubicweb/cubes/shared/data
usr/share/cubicweb/cubes/shared/wdoc