Add a migration to add project permissions to blob documents

Create a new Advanced Search migration which queues all blob documents for indexing when they are missing any of the project permission data (visibility_level and repository_visibility_level).

Note: This may require re-indexing of the entire project. Consider whether it's possible to:

• use the initial indexing queue to not affect normal indexing processes
• update the documents using Elasticsearch in an Advanced Search migration to avoid going through the elasticsearch indexer