[dataimport] add tests for SQLGenObjectStore (closes #9177565) Stolen from the massive import store, with the irrelevant bits removed. Remove redundant tests from test_pgstore.py.

usr/bin/cubicweb-ctl usr/bin/
usr/lib/python2*/*-packages/cubicweb/cwctl.py
../cubicweb-ctl.bash_completion etc/bash_completion.d/cubicweb-ctl