Update export/import to work with job definitions and new destinations

When we export a project, we also export all of its pipelines and jobs. These can be imported in a different GitLab instance. We need to ensure the deduplication for the data on the import.

Proposal

Keep exporting jobs as we do now, for each job export all of the metadata. On import find or create new job definitions based to the metadata and write to new destinations. For example: to new columns of ci_builds, etc.