[Improvement]: PostSaveFailEvent upon failing to import a queued item

[RickardAhlstedt]

Improvement description

In data-importer we currently have two events, which is PreSaveEvent and PostSaveEvent, which we can listen for successfull import of an item, but we have no event to listen for if an item fails to import.
Having such an event can enable (example) use-cases:

• Notifying users about a failed import either via e-mail or a notification without having the user trying to read the error in either the import-log or the application-log.
• Automatic options, such as still creating the item, but without the data that is faulty.

Implementation:
This can be implemented in src/Processing/ImportProcessingService.php in function processElement on line 247 and 257.
Note: I have version 1.4 of data-importer running in Pimcore 10.6, actual filenames and line-numbers may have changed in this repo.

[github-actions]

Thanks a lot for reporting the issue. We did not consider the issue as "Pimcore:Priority", "Pimcore:ToDo" or "Pimcore:Backlog", so we're not going to work on that anytime soon. Please create a pull request to fix the issue if this is a bug report. We'll then review it as quickly as possible. If you're interested in contributing a feature, please contact us first here before creating a pull request. We'll then decide whether we'd accept it or not. Thanks for your understanding.