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/utils/background_sync.dart

@@ -59,6 +59,28 @@ class BackgroundSyncManager {
     }
   }
 
+  Future<void> cancelLocal() async {
+    final futures = <Future>[];
+
+    if (_hashTask != null) {
+      futures.add(_hashTask!.future);
+    }
+    _hashTask?.cancel();
+    _hashTask = null;
+
+    if (_deviceAlbumSyncTask != null) {
+      futures.add(_deviceAlbumSyncTask!.future);
+    }
+    _deviceAlbumSyncTask?.cancel();
+    _deviceAlbumSyncTask = null;
+
+    try {
+      await Future.wait(futures);
+    } on CanceledError {
+      // Ignore cancellation errors
+    }
+  }
+
   // No need to cancel the task, as it can also be run when the user logs out
   Future<void> syncLocal({bool full = false}) {
     if (_deviceAlbumSyncTask != null) {