TF-3515 Add save email as template feature

lib/features/email/data/datasource_impl/email_datasource_impl.dart

@@ -221,6 +221,46 @@ class EmailDataSourceImpl extends EmailDataSource {
     }).catchError(_exceptionThrower.throwException);
   }
 
+  @override
+  Future<Email> saveEmailAsTemplate(
+    Session session,
+    AccountId accountId,
+    Email email,
+    {
+      CreateNewMailboxRequest? createNewMailboxRequest,
+      CancelToken? cancelToken
+    }
+  ) {
+    return Future.sync(() async {
+      return await emailAPI.saveEmailAsTemplate(
+        session,
+        accountId,
+        email,
+        createNewMailboxRequest: createNewMailboxRequest,
+        cancelToken: cancelToken
+      );
+    }).catchError(_exceptionThrower.throwException);
+  }
+
+  @override
+  Future<Email> updateEmailTemplate(
+    Session session,
+    AccountId accountId,
+    Email newEmail,
+    EmailId oldEmailId,
+    {CancelToken? cancelToken}
+  ) {
+    return Future.sync(() async {
+      return await emailAPI.updateEmailTemplate(
+        session,
+        accountId,
+        newEmail,
+        oldEmailId,
+        cancelToken: cancelToken
+      );
+    }).catchError(_exceptionThrower.throwException);
+  }
+
   @override
   Future<Uint8List> downloadAttachmentForWeb(
       DownloadTaskId taskId,

lib/features/email/data/datasource_impl/email_hive_cache_datasource_impl.dart

@@ -275,6 +275,36 @@ class EmailHiveCacheDataSourceImpl extends EmailDataSource {
     return email;
   }
 
+  @override
+  Future<Email> saveEmailAsTemplate(
+    Session session,
+    AccountId accountId,
+    Email email,
+    {
+      CreateNewMailboxRequest? createNewMailboxRequest,
+      CancelToken? cancelToken
+    }
+  ) async {
+    await _emailCacheManager.update(accountId, session.username, created: [email]);
+    return email;
+  }
+
+  @override
+  Future<Email> updateEmailTemplate(
+    Session session,
+    AccountId accountId,
+    Email newEmail,
+    EmailId oldEmailId,
+    {CancelToken? cancelToken}
+  ) async {
+    await _emailCacheManager.update(
+      accountId,
+      session.username,
+      updated: [newEmail],
+    );
+    return newEmail;
+  }
+
   @override
   Future<bool> sendEmail(
     Session session,

lib/features/email/data/datasource_impl/email_local_storage_datasource_impl.dart

@@ -355,4 +355,26 @@ class EmailLocalStorageDataSourceImpl extends EmailDataSource {
       return htmlDocument;
     }).catchError(_exceptionThrower.throwException);
   }
+  
+  @override
+  Future<Email> saveEmailAsTemplate(
+    Session session,
+    AccountId accountId,
+    Email email, {
+    CreateNewMailboxRequest? createNewMailboxRequest,
+    CancelToken? cancelToken,
+  }) {
+    throw UnimplementedError();
+  }
+  
+  @override
+  Future<Email> updateEmailTemplate(
+    Session session,
+    AccountId accountId,
+    Email newEmail,
+    EmailId oldEmailId, {
+    CancelToken? cancelToken,
+  }) {
+    throw UnimplementedError();
+  }
 }

lib/features/email/data/datasource_impl/email_session_storage_datasource_impl.dart

@@ -271,4 +271,26 @@ class EmailSessionStorageDatasourceImpl extends EmailDataSource {
   Future<String> generateEntireMessageAsDocument(ViewEntireMessageRequest entireMessageRequest) {
     throw UnimplementedError();
   }
+  
+  @override
+  Future<Email> saveEmailAsTemplate(
+    Session session,
+    AccountId accountId,
+    Email email, {
+    CreateNewMailboxRequest? createNewMailboxRequest,
+    CancelToken? cancelToken,
+  }) {
+    throw UnimplementedError();
+  }
+  
+  @override
+  Future<Email> updateEmailTemplate(
+    Session session,
+    AccountId accountId,
+    Email newEmail,
+    EmailId oldEmailId, {
+    CancelToken? cancelToken,
+  }) {
+    throw UnimplementedError();
+  }
 }