[Host.Outbox] Transactional outbox plugin with MS SQL / Azure SQL support

[zarusz]

We would like to have the ability for SMB to support Transaction outbox pattern out of box:

• The message producer declaration would indicate it should go via an outbox persisted on SQL table
• SMB upon publish would insert the record into the SQL table which would be part of the ongoing transaction
• SMB in another task would poll messages from the SQL table and deliver to the underlying messaging transport.

[zarusz]

The feature is released.