Navbarextensions improvements (#9871)

* - added controller option
- added $location service to determine on which the user is at currently

* added test for the hideButton method that is dependent on the location path

* removed  argument

* use locals object to pass variables to the template's scope

* use map object

src/ui/public/kbn_top_nav/kbn_top_nav_controller.js

@@ -18,6 +18,7 @@ export default function ($compile) {
         interval: intervalTemplate,
         filter: filterTemplate,
       };
+      this.locals = new Map();
 
       this.addItems(opts);
     }
@@ -35,6 +36,9 @@ export default function ($compile) {
         this.opts.push(opt);
         if (!opt.hideButton()) this.menuItems.push(opt);
         if (opt.template) this.templates[opt.key] = opt.template;
+        if (opt.locals) {
+          this.locals.set(opt.key, opt.locals);
+        }
       });
     }
 
@@ -107,6 +111,9 @@ export default function ($compile) {
       }
 
       const $childScope = $scope.$new();
+      if (this.locals.has(currentKey)) {
+        Object.assign($childScope, this.locals.get(currentKey));
+      }
       const $el = $element.find('#template_wrapper').html(templateToRender).contents();
       $compile($el)($childScope);