Add Hook to Allow Entities to Be Acted Upon During Import

Problem/Motivation

In some cases it would be beneficial to act on entities that are about to be imported.

Steps to reproduce

N/A

Proposed resolution

Add the module handler to the importer service and invoke hook_default_content_import.

Remaining tasks

• Add default_content.api.php file describing the additional hook.
• Add tests.

User interface changes

None.

API changes

Adds a hook_default_content_import() which other extensions may implement to act on the entity import.

Data model changes

None.