Enable user to control the column sizes

[JocaPC]

Maybe it would be useful to introduce fields like ColumnOptions.Message.Size and ColumnOptions.Level.Size that would enable users to control column size. Also, it might be more flexible to have Id.Size instead of Id.Bigint (but I guess that everyone will use either int or bigint so this is fine.)

Also, why is Level defined as nvarchar(128) instead of varchar(12), which should be sufficient to store "Information" level? Query Optimizer looks at the statistic about the number of rows and size of columns to calculate memory grant that should be assigned to query. Adding too big types might cause that queries on log table eat too much memory that they don't use, and starve other queries.

[MV10]

In general, I don't like the way this sink has one group of properties for the standard columns and a completely different group of properties for custom columns (which do have DataLength), but that's probably one of those things that will never change now for compatibility reasons...

[MV10]

Currently overhauling sink configuration -- remaining backwards compatible but marking some things obsolete, Standard Columns and custom columns will be configured in the same way, and controlling the size of everything is one small piece of the puzzle.