Before this, there was one code path that set `context.export_path`, and a different code path for `context.export_name`, allowing the two to diverge. Keeping track of the export path of the export parent (which can be, but is not always, the Blender parent object) also allows a concrete subclass of `AbstractHierarchyIterator` to find the `AbstractWriter` for the export parent. In case of exporting to Alembic this is important, as it's not possible to simply give the Alembic library the full export path of an object like we do in the Universal Scene Description (USD) exporter; Alembic needs the C++ object of the parent.