Quantity agent property probe doesnt work

[etatara]

RS 2.9.1 and earlier use to be able to show probed agent properties for Amount class, and we updated the Java Units API to Quantity class, and discovered that this functionality appears to be non-working for awhile, e.g. this doesnt work in 2.9.1 and earlier. There appear to unused older classes in r.s.ui.probe and the functionality for creating probes on Amount/Quantity wasn't carried over. Need to think if maintaining probes for Quantities makes sense longer term.