materialize
Materializes this NamedAggregate into a MaterializedNamedAggregate.
This extension function converts any NamedAggregate implementation into its materialized form. If the aggregate is already materialized, it returns itself. If it's a decorator, it recursively materializes the underlying aggregate. Otherwise, it creates a new MaterializedNamedAggregate with the context and aggregate names.
Return
A MaterializedNamedAggregate representing this named aggregate.