feat: [UEPR-245] export legacy storage

Author: MiroslavDionisiev

packages/scratch-gui/src/index-standalone.tsx

@@ -8,6 +8,7 @@ import {compose} from 'redux';
 
 export {EditorState, EditorStateParams} from './lib/editor-state';
 export {AccountMenuOptions} from './lib/account-menu-options';
+export {LegacyStorage} from './lib/legacy-storage';
 
 export {setAppElement} from 'react-modal';