Refacor electron app and add migrations

electron/entities/index.ts

@@ -0,0 +1,7 @@
+export { MessageEntity } from './MessageEntity';
+export { UserEntity } from './UserEntity';
+export { RoomEntity } from './RoomEntity';
+export { ReactionEntity } from './ReactionEntity';
+export { BanEntity } from './BanEntity';
+export { AttachmentEntity } from './AttachmentEntity';
+export { MetaEntity } from './MetaEntity';