feat: task file manage (#196)

1. support view task file list
2. support share file on android and iOS

ui/flutter/lib/app/modules/task/bindings/task_files_binding.dart

@@ -0,0 +1,12 @@
+import 'package:get/get.dart';
+
+import '../controllers/task_files_controller.dart';
+
+class TaskFilesBinding extends Bindings {
+  @override
+  void dependencies() {
+    Get.lazyPut<TaskFilesController>(
+      () => TaskFilesController(),
+    );
+  }
+}