SQL Server adapter still uses text and ntext types, despite deprecation

[atbigelow]

According to MS's documentation for SQL Server 2017, ntext and text are deprecated and pending removal. It has been official guidance to use varchar(max) and nvarchar(max) for years instead of these types.

The use of these old types also requires SQL to be written to cast or convert when comparing strings, further encouraging the need for this to be changed.

The adapter should be changed to generate varchar(max) and nvarchar(max) instead of text and ntext.