Add SQL Server TIMESTAMP / ROWVERSION datatypes

Add SQL Server TIMESTAMP / ROWVERSION datatypes

SQL Server has an entirely different use for the TIMESTAMP
datatype that is unrelated to the SQL standard's version of this
type.   It is a read-only type that returns an incrementing
binary value.  The ROWVERSION name will supersede the TIMESTAMP
name.  Implement datatype objects for both, separate from the
base DateTime/TIMESTAMP class hierarchy, and also implement
an optional integer coercion feature.

Change-Id: Ie2bd43b7aac57760b8ec6ff6e26460e2086a95eb
Fixes: #4086