Add ability to "watch" a Develop team and team line

In Roadmaps, I can "watch" an entire workspace (set in Strategy > Overview). I don't have this same capability in Develop.

This was problematic to me personally recently because I missed that someone had created a new PI, and it took me a long time to realize why our sprint planning page looked odd and I couldn't delete those sprints. I would like to be apprised of changes people make as they happen so I don't have to do too much sleuthing later on.