Add 2.x field identifiers support for SQLColAttribute

Add support for the required 2.x fields, as per the [Backward Compatibility](https://docs.microsoft.com/en-us/sql/odbc/reference/syntax/sqlcolattribute-function#backward-compatibility) section: `An ODBC 3.x driver must support both "SQL_COLUMN" and "SQL_DESC" values for these three FieldIdentifiers.` (i.e. SQL_COLUMN_LENGTH, SQL_COLUMN_PRECISION, and SQL_COLUMN_SCALE)