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/pigeon/background_worker_api.dart

@@ -0,0 +1,48 @@
+import 'package:pigeon/pigeon.dart';
+
+@ConfigurePigeon(
+  PigeonOptions(
+    dartOut: 'lib/platform/background_worker_api.g.dart',
+    swiftOut: 'ios/Runner/Background/BackgroundWorker.g.swift',
+    swiftOptions: SwiftOptions(includeErrorClass: false),
+    kotlinOut: 'android/app/src/main/kotlin/app/alextran/immich/background/BackgroundWorker.g.kt',
+    kotlinOptions: KotlinOptions(package: 'app.alextran.immich.background'),
+    dartOptions: DartOptions(),
+    dartPackageName: 'immich_mobile',
+  ),
+)
+@HostApi()
+abstract class BackgroundWorkerFgHostApi {
+  void enableSyncWorker();
+
+  // Enables the background upload service with the given callback handle
+  void enableUploadWorker(int callbackHandle);
+
+  // Disables the background upload service
+  void disableUploadWorker();
+}
+
+@HostApi()
+abstract class BackgroundWorkerBgHostApi {
+  // Called from the background flutter engine when it has bootstrapped and established the
+  // required platform channels to notify the native side to start the background upload
+  void onInitialized();
+}
+
+@FlutterApi()
+abstract class BackgroundWorkerFlutterApi {
+  // Android & iOS: Called when the local sync is triggered
+  @async
+  void onLocalSync(int? maxSeconds);
+
+  // iOS Only: Called when the iOS background upload is triggered
+  @async
+  void onIosUpload(bool isRefresh, int? maxSeconds);
+
+  // Android Only: Called when the Android background upload is triggered
+  @async
+  void onAndroidUpload();
+
+  @async
+  void cancel();
+}