General config/SQL mismatches for custom columns

[MV10]

Custom column configuration in the old .NET Framework code accepts a DataLength property which is never applied to the resulting DataColumn.MaxLength property for Binary and VarBinary column data types. (It is applied properly for the various character column types such as NVarChar.)

In general, I'm overhauling how additional columns are created, so I'll end up fixing this at the same time.

[MV10]

Some column types wind up as different types upon auto-create. ConvertSqlDataTypecs (yes the filename has a typo) converts a SQL decimal to a .NET decimal (which is correct) but then upon auto table creation SqlTableCreator converts that to a SQL real column.

There are other issues, such as accepting a SQL time column which has no corresponding match in SqlTableCreator.

The overhaul will unify things so that config exclusively uses CommonColumnOptions and only references SQL data types in config (including config-by-code) and the use of DataColumn will be a purely internal matter. An ExtendedProperties key SqlType will track the real SQL data type so that it isn't lost when it gets dumbed-down to the .NET System.Type equivalents.

As a result the older AdditionalDataColumns will be deprecated in favor of the new CommonColumnOptions-based AdditionalColumns.