[Plot] Add switcher for Stacked/Overlaid

Add switcher to handle changing between Stacked and Overlaid
plots. WTD-625.

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

@@ -0,0 +1,36 @@
+/*global define*/
+
+define(
+    [],
+    function (PlotOverlayMode, PlotStackedMode) {
+        "use strict";
+
+        var STACKED = {
+                key: "stacked",
+                name: "Stacked",
+                glyph: "8"
+            },
+            OVERLAID = {
+                key: "overlaid",
+                name: "Overlaid",
+                glyph: "6"
+            };
+
+        function PlotModeOptions(telemetryObjects) {
+            var options = telemetryObjects.length > 1 ?
+                    [ STACKED, OVERLAID ] : [ OVERLAID, STACKED ];
+
+
+            return {
+                getModeOptions: function () {
+                    return options;
+                },
+                getMode: function (option) {
+
+                }
+            };
+        }
+
+        return PlotModeOptions;
+    }
+);