Disable metadata switch if only one item is available

Single metadata item on image details looks like action button,
which is confusing, so change cursor from pointer to default.

Closes-Bug: #1731884
Change-Id: I50b9a9c3878866249561a58c92aeafff4dffc949
Co-Authored-By: Ivan Kolodyazhny <e0ne@e0ne.info>

horizon/static/framework/widgets/metadata/display/display.scss

@@ -3,9 +3,10 @@
     .selector-item {
       padding: $padding-base-vertical $padding-base-horizontal;
       color: $link-color;
-      cursor: pointer;
       border-radius: $nav-pills-border-radius;
-
+      &.clickable {
+        cursor: pointer;
+      }
       &.active {
         background: $nav-pills-active-link-hover-bg;
         color: $nav-pills-active-link-hover-color;

horizon/static/framework/widgets/metadata/display/metadata-display.controller.js

@@ -76,6 +76,13 @@
           return true; // break
         }
       });
+
+      ctrl.count = 0;
+      ctrl.tree.flatTree.some(function (i) {
+        if (ctrl.listFilter(i)) {
+          ctrl.count += 1;
+        }
+      });
     }
   }
 })();

horizon/static/framework/widgets/metadata/display/metadata-display.html

@@ -4,7 +4,7 @@
       <div class="selector-item"
            ng-repeat="item in ctrl.tree.flatTree | filter: ctrl.listFilter"
            ng-click="ctrl.onSelect(item)"
-           ng-class="{ active: ctrl.selected === item }">
+           ng-class="{ active: ctrl.selected === item, clickable: ctrl.count > 1 }">
         <span ng-bind="::item.label"></span>
       </div>
     </div>