planner needs way to report events that it's waiting for

[davepacheco]

Copying from #8261 (comment):

I am imagining that the we'll want to have an accumulator for "things that we're waiting for right now". Any time we bail out of a planning path (like we do here) because we're waiting on some condition, we'll want to append to that. Then I think we want to be able to report that with the upgrade status.