[BUGFIX] Test whether the current entity matches a privilege
This decouples the check, whether a query has to be modified by a
``EntityPrivilege`` SQL constraint from the generation of the actual
By this it is possible to skip not matching privileges before the SQL
One use case for this is an ``EntityPrivilege`` with a fixed entity
type, where no matcher expression has to be evaluated to check the
target entity type.
Additionally this adds a ``FalseConditionGenerator`` to be able to add
a FALSE condition part in the SQL generation process.
Furthermore this renames the ``AnyEntityConditionGenerator`` to
``TrueConditionGenerator`` respectively for consistency reasons.
Releases: master, 3.0