feat: feature flag in settings page (#4833)

frontend/appflowy_flutter/lib/startup/tasks/feature_flag_task.dart

@@ -0,0 +1,21 @@
+import 'package:appflowy/shared/feature_flags.dart';
+import 'package:flutter/foundation.dart';
+
+import '../startup.dart';
+
+class FeatureFlagTask extends LaunchTask {
+  const FeatureFlagTask();
+
+  @override
+  Future<void> initialize(LaunchContext context) async {
+    // the hotkey manager is not supported on mobile
+    if (!kDebugMode) {
+      return;
+    }
+
+    await FeatureFlag.initialize();
+  }
+
+  @override
+  Future<void> dispose() async {}
+}