Monitor or Stop Monitoring Git Repositories

Sets repositories to monitored or not_monitored, up to 100 per call, exactly as Settings > Git > Repositories does. Monitoring starts collecting the repository and loads its history; it counts against the repository quota. Stopping monitoring stops collecting new data; data already collected is kept. Each repository is applied or rejected on its own: a repository already in the requested state is applied, and a rejected one carries a code and a message.