Use device storage for allowed widgets if account data not supported

With guest accounts, account data is not available, so we use device storage to
hold allowed widgets as a good enough place.

Fixes https://github.com/vector-im/element-web/issues/16145

src/settings/Settings.ts

@@ -421,7 +421,8 @@ export const SETTINGS: {[setting: string]: ISetting} = {
         default: true,
     },
     "allowedWidgets": {
-        supportedLevels: [SettingLevel.ROOM_ACCOUNT],
+        supportedLevels: [SettingLevel.ROOM_ACCOUNT, SettingLevel.ROOM_DEVICE],
+        supportedLevelsAreOrdered: true,
         default: {}, // none allowed
     },
     "analyticsOptIn": {