[Plot] Initially implement synced pan/zoom stack

Initially implement a synchronized pan/zoom stack,
which maintains the same domain axis bounds for all
subplots in a stacked plot view, but allows each to
have independent range axes. WTD-625.

platform/features/plot/src/modes/PlotOverlayMode.js

@@ -45,7 +45,7 @@ define(
                     return panZoomStack.getDepth() > 1;
                 },
                 stepBackPanZoom: function () {
-                    panZoomStack.pop();
+                    panZoomStack.popPanZoom();
                     subplot.update();
                 },
                 unzoom: function () {