TF-886 Store encryptionKey in Hive database

lib/features/login/data/model/encryption_key_cache.dart

@@ -0,0 +1,19 @@
+import 'package:equatable/equatable.dart';
+import 'package:hive/hive.dart';
+import 'package:tmail_ui_user/features/caching/utils/caching_constants.dart';
+
+part 'encryption_key_cache.g.dart';
+
+@HiveType(typeId: CachingConstants.ENCRYPTION_KEY_HIVE_CACHE_IDENTIFY)
+class EncryptionKeyCache extends HiveObject with EquatableMixin {
+
+  static const String keyCacheValue = 'hiveEncryptionKey';
+
+  @HiveField(0)
+  final String value;
+
+  EncryptionKeyCache(this.value);
+
+  @override
+  List<Object?> get props => [value];
+}