gui: Display rescan button when out of sync and remove deprecated folder state

GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4704

gui/default/index.html

@@ -439,7 +439,7 @@
                   <button type="button" class="btn btn-default btn-sm" ng-click="restoreVersions.show(folder.id)" ng-if="folder.versioning.type">
                     <span class="fa fa-undo"></span>&nbsp;<span translate>Versions</span>
                   </button>
-                  <button type="button" class="btn btn-sm btn-default" ng-click="rescanFolder(folder.id)" ng-show="['idle', 'stopped', 'unshared'].indexOf(folderStatus(folder)) > -1">
+                  <button type="button" class="btn btn-sm btn-default" ng-click="rescanFolder(folder.id)" ng-show="['idle', 'stopped', 'unshared', 'outofsync'].indexOf(folderStatus(folder)) > -1">
                     <span class="fa fa-refresh"></span>&nbsp;<span translate>Rescan</span>
                   </button>
                   <button type="button" class="btn btn-sm btn-default" ng-click="editFolder(folder)">

gui/default/syncthing/core/syncthingController.js

@@ -731,10 +731,6 @@ angular.module('syncthing.core')
                 return 'unknown';
             }
 
-            if ($scope.model[folderCfg.id].invalid) {
-                return 'stopped';
-            }
-
             var state = '' + $scope.model[folderCfg.id].state;
             if (state === 'error') {
                 return 'stopped'; // legacy, the state is called "stopped" in the GUI