Reactor step: apply actor-scoped Ash policy filtering to the mapping bundle.
When actor is nil the bundle passes through unchanged. Otherwise
AshR2RML.Policy.filter_for_actor/3 is called, which omits predicate-object
maps and reference-object maps the actor is not authorized to read.
Arguments
:bundle—%AshR2RML.Mapping.Bundle{}enriched with provenance maps.:actor— optional actor map;nildisables filtering.