TF-3416 Persist preview EML content when make reload page action

lib/features/caching/utils/session_storage_manager.dart

@@ -0,0 +1,27 @@
+
+import 'package:collection/collection.dart';
+import 'package:tmail_ui_user/features/caching/exceptions/local_storage_exception.dart';
+import 'package:universal_html/html.dart' as html;
+
+class SessionStorageManager {
+
+  void save(String key, String value) {
+    html.window.sessionStorage.addAll({key: value});
+  }
+
+  String get(String key) {
+    final entry = html.window.sessionStorage
+      .entries
+      .firstWhereOrNull((entry) => entry.key == key);
+
+    if (entry != null) {
+      return entry.value;
+    } else {
+      throw NotFoundDataWithThisKeyException();
+    }
+  }
+
+  void remove(String key) {
+    html.window.sessionStorage.remove(key);
+  }
+}