feat: Add feature flag for refresh tokens

lib/config/setting_keys.dart

@@ -57,7 +57,8 @@ enum AppSettings<T> {
   displayChatDetailsColumn(
     'chat.fluffy.display_chat_details_column',
     false,
-  );
+  ),
+  enableSoftLogout<bool>('chat.fluffy.enable_soft_logout', false);
 
   final String key;
   final T defaultValue;

lib/utils/client_manager.dart

@@ -102,6 +102,7 @@ abstract class ClientManager {
 
   static Client createClient(String clientName, SharedPreferences store) {
     final shareKeysWith = AppSettings.shareKeysWith.getItem(store);
+    final enableSoftLogout = AppSettings.enableSoftLogout.getItem(store);
 
     return Client(
       clientName,
@@ -130,6 +131,8 @@ abstract class ClientManager {
               .singleWhereOrNull((share) => share.name == shareKeysWith) ??
           ShareKeysWith.all,
       convertLinebreaksInFormatting: false,
+      onSoftLogout:
+          enableSoftLogout ? (client) => client.refreshAccessToken() : null,
     );
   }