Improve accessibility by adding alternative text for screen-readers. (#11548)

* Ensure img elements have alt text where necessary (none do).
- Add aria-hidden to global nav icon.

* Remove unused title attribute from SavedObjectFinder.

src/core_plugins/kibana/public/dashboard/top_nav/add_panel.html

@@ -25,7 +25,6 @@
 
   <div class="list-group-item list-group-item--noBorder" ng-switch-when="visualization">
     <saved-object-finder
-      title="Choose a visualization"
       use-local-management="true"
       type="visualizations"
       on-add-new="opts.addNewVis"
@@ -34,6 +33,10 @@
   </div>
 
   <div class="list-group-item list-group-item--noBorder" ng-switch-when="search">
-    <saved-object-finder title="Choose a search" type="searches" use-local-management="true" on-choose="opts.addSearch"></saved-object-finder>
+    <saved-object-finder
+      type="searches"
+      use-local-management="true"
+      on-choose="opts.addSearch"
+    ></saved-object-finder>
   </div>
 </div>

src/core_plugins/kibana/public/visualize/wizard/step_2.html

@@ -34,7 +34,6 @@
 
       <!-- Saved searches -->
       <saved-object-finder
-        title="Saved Searches"
         type="searches"
         class="wizard-row visualizeWizardSavedObjectFinder kuiVerticalRhythm"
         make-url="step2WithSearchUrl"

src/ui/public/chrome/directives/global_nav/global_nav_link/global_nav_link.html

@@ -13,12 +13,11 @@
     data-test-subj="appLink"
   >
     <div class="global-nav-link__icon">
-      <!-- Empty alt attribute is for accessibility -->
       <img
         ng-if="icon"
         class="global-nav-link__icon-image"
         kbn-src="{{ '/' + icon }}"
-        alt=""
+        aria-hidden
       >
 
       <span

src/ui/public/directives/saved_object_finder.js

@@ -15,7 +15,6 @@ module.directive('savedObjectFinder', function ($location, $injector, kbnUrl, Pr
     restrict: 'E',
     scope: {
       type: '@',
-      title: '@?',
       // optional make-url attr, sets the userMakeUrl in our scope
       userMakeUrl: '=?makeUrl',
       // optional on-choose attr, sets the userOnChoose in our scope