Add observability and actionability to repository admin page

Created by: eugeniaft

Display in repository admin page:

• indexing status of repository
• where in the queue a repository is
• how long it has been in the queue
• time of last indexing job
• files that are not indexed within that repository
• action to manually trigger index of a repo
• option to include a file to index
• option to index additional branches
• option to alert admin when a repo has not successfully indexed