[querier/security] instrument a bit the querier read security checks
Related to #2920304
What's new in CubicWeb 3.18?============================New functionalities--------------------* add a security debugging tool (see `#2920304 <http://www.cubicweb.org/2920304>`_)API changes-----------* not really an API change, but the entity permission checks are now systematically deferred to an operation, instead of a) trying in a hook and b) if it failed, retrying later in an operationDeprecation---------------------Deprecated Code Drops----------------------*``ldapuser`` have been dropped; use ``ldapfeed`` now (see `#2936496 <http://www.cubicweb.org/2936496>`_)* all 3.8 backward compat is gone* all 3.9 backward compat (including the javascript side) is gone