[Feature] MS SQL Inbox and Outbox DDL NText is deprecated

[holytshirt]

https://learn.microsoft.com/en-us/sql/t-sql/data-types/ntext-text-and-image-transact-sql

The ntext, text, and image data types will be removed in a future version of SQL Server. Avoid using these data types in new development work, and plan to modify applications that currently use them. Use nvarchar(max), varchar(max), and varbinary(max) instead.

The DDL we provided for Inbox and Outbox uses NText to store body and header

Inbox
https://github.com/BrighterCommand/Brighter/blob/master/src/Paramore.Brighter.Inbox.MsSql/DDL%20Scripts/MSSQL/Inbox.sql
https://github.com/BrighterCommand/Brighter/blob/master/src/Paramore.Brighter.Inbox.MsSql/SqlInboxBuilder.cs#L38

OutBox
https://github.com/BrighterCommand/Brighter/blob/master/src/Paramore.Brighter.Outbox.MsSql/DDL_SCRIPTS/MSSQL/Outbox.sql
https://github.com/BrighterCommand/Brighter/blob/master/src/Paramore.Brighter.Outbox.MsSql/SqlOutboxBuilder.cs

[iancooper]

@holytshirt Can pick up as part of work to support a binary outbox.