Show a throbber when the Angular view array still has hidden entries

This provides slightly better UI feedback to the user that more logs are incoming

Fixes #1881

static/directives/build-logs-view.html

@@ -64,6 +64,9 @@
           <span class="message" bo-html="processANSI(entry.message, container)"></span>
           <span class="timestamp" bo-text="formatDatetime(entry.data.datetime)" ng-if="!useTimestamps"></span>
         </div>
+        <div ng-if="container.logs.hasHiddenEntries">
+          <div class="cor-loader-inline"></div>
+        </div>
       </div>
     </div>
   </div>