cmd/syncthing, gui: Implement download of "support bundle" (fixes #5142) (#5145)

gui/default/index.html

@@ -81,6 +81,8 @@
             <li class="divider" aria-hidden="true"></li>
             <li><a href="" ng-click="advanced()"><span class="fas fa-fw fa-cogs"></span>&nbsp;<span translate>Advanced</span></a></li>
             <li><a href="" ng-click="logging.show()"><span class="far fa-fw fa-file-alt"></span>&nbsp;<span translate>Logs</span></a></li>
+            <li class="divider" aria-hidden="true" ng-if="config.gui.debugging"></li>
+            <li><a href="/rest/debug/support" target="_blank" ng-if="config.gui.debugging"><span class="fa fa-user-md"></span>&nbsp;<span translate>Support Bundle</span></li>
           </ul>
         </li>
       </ul>