Operator View: Updates - what version is available?

[smklein]

The operator API should provide a way of identifying, in addition to #2038 , what version we could update to. This could be as simple as "updates available", but should probably be more nuanced than that.

[david-crespo]

API side of this is closed by #2100. I will likely add another issue (if there isn't already one) representing populating this data correctly.