feat: beta background sync (#21243)

* feat: ios background sync

# Conflicts:
#	mobile/ios/Runner/Info.plist

* feat: Android sync

* add local sync worker and rename stuff

* group upload notifications

* uncomment onresume beta handling

* rename methods

---------

Co-authored-by: shenlong-tanwen <139912620+shalong-tanwen@users.noreply.github.com>
Co-authored-by: Alex <alex.tran1502@gmail.com>

mobile/lib/domain/services/log.service.dart

@@ -123,6 +123,11 @@ class LogService {
     _flushTimer = null;
     final buffer = [..._msgBuffer];
     _msgBuffer.clear();
+
+    if (buffer.isEmpty) {
+      return;
+    }
+
     await _logRepository.insertAll(buffer);
   }
 }