Break out storage usage when NiFi is clustered

When NiFi is clustered, the defined repositories storage usage across multiple Nodes are all summed together in the "System Diagnoistics" UI. While it is possible to see an individual Nodes usage by changing the "NiFi Summary" to "Single Node" view, it is not very user friendly. It also make seeing an existing or pending issue harder for the end user to see. For example, the UI may show that Content or Flowfile storage usage is only at 70%, but that could equate to 99% on one Node and only 41% on another. I believe all repos should be broken out on to separate lines in the UI when clustered making it easier to read by the end user.