[dataimport] Fallback from COPY to executemany (closes #9135780)
If we can't build a suitable COPY command (e.g. because data has
unsupported type), use executemany instead. Regression introduced in
3.20.0.
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