Refacor electron app and add migrations

electron/cqrs/commands/handlers/deleteAttachmentsForMessage.ts

@@ -0,0 +1,9 @@
+import { DataSource } from 'typeorm';
+import { AttachmentEntity } from '../../../entities';
+import { DeleteAttachmentsForMessageCommand } from '../../types';
+
+export async function handleDeleteAttachmentsForMessage(command: DeleteAttachmentsForMessageCommand, dataSource: DataSource): Promise<void> {
+  const repo = dataSource.getRepository(AttachmentEntity);
+
+  await repo.delete({ messageId: command.payload.messageId });
+}