MAGETWO-71835: [Product grid] SC's values aren't sorted alphabetically in the tooltip

- Sort values case insensitive

Author: VeronikaYarats

app/code/Magento/Ui/view/base/web/js/grid/columns/expandable.js

@@ -67,7 +67,11 @@ define([
                 }
             });
 
-            return labels.sort();
+            return labels.sort(
+                function(a, b) {
+                    return a.toLowerCase().localeCompare(b.toLowerCase());
+                }
+            );
         },
 
         /**