Fix MS SQL Driver to not show warnings for version fetching on connection and to retrieve the next set of results properly

When trying to connect, the redirect didn't happen properly for me because the connect query caused warnings about an unset type.

Connect statement: https://github.com/wiseloren/adminer/blob/05743711db172c66bffc2c66f48f3cbe21a159ad/adminer/drivers/mssql.inc.php#L149

I resolved this by placing an @ before the mssql_query statement so the warnings are suppressed.
Secondly, the result is placed in the Min_result class so fetching the next result needs to be done with $this->_result->_result