Expose github "hard_failures" through import status API

Context

We already have a projects/:id/import (https://docs.gitlab.com/ee/api/project_import_export.html#import-status) to expose the import status of the given project. This endpoint exposes "hard_failures", which are errors that caused the import to fail.

Proposal

Change the Gitlab::Import::ImportFailureService to create the failure record with the retry_count: 0, when it's failing the import. The retry_count: 0 is is the condition to expose the failure as a "hard_failure" in the API.