deprecate get/set_shared_data API
Session or transaction data must be used instead.
We must forward .transaction_data to web/request from
which it was missing (this is indeed a _cw object API).
Closes #3799036.
usr/lib/PY_VERSION/*-packages/cubicweb/entities/
usr/lib/PY_VERSION/*-packages/cubicweb/ext/
usr/share/cubicweb/cubes/
usr/lib/PY_VERSION/*-packages/cubicweb/*.py