PostImportEvent after all content imported

Problem/Motivation

When an entity has been saved via import there isn’t a great way to know in hook_entity_save if it was from an import and setting it as sync may not be great. So a PostImportEvent would be great that has Finder $content and the array of created entities.|

Steps to reproduce

Proposed resolution

Dispatch PostImportEvent once all content has been imported

Remaining tasks

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet