Implement new curation workflow

This MR adds support for the new Invenio-Curations-based submission review workflow. Some configuration is updated to enable the workflow, and the customized permissions are updated to match the new expectations. ⚠ Note that some parts of the workflow aren't managed by permissions but rather via system components!

This MR also adds an automatic review by the system (optionally a simple "accept"), and a few tweaks for the notifications: The email notifications will now include a custom email header value that indicates the sender system, to help with automatic mail processing rules. Also, reminder emails will be sent to reviewers for stale open requests, and to uploaders about accepted but still unpublished records.