Schema:
- `id`: this is a field working as autoincrement, in queries we'll pass it as `NULL`, and SQLite engine will automatically assign it to track messages order ([docs](https://www.sqlite.org/autoinc.html))
- `message_id`: message ID needed to later confirm to the other peer that the message was processed/backed up
- `sender_device_id`: messages sender
- `plaintext`: decrypted messages
- `status`: messages status to distinguish in what phase this message is, it will be something like `received | processed | backup-done`