Add bind test for Visual C++/COM _variant_t as input parameter.
Add bind test for Visual C++/COM _variant_t as input parameter.

The test is specific to Windows/Visual C++.
Although it is not SQL Server-specific and it could be executed
against all the tested databases, it has been added to SQL Server
tests only for simplicity.

ChrisBFX/nanodbc,ChrisBFX/nanodbc,nanodbc/nanodbc,nanodbc/nanodbc