Add MapOrdinal method to the IDataTransformer interface and provide
a default implementation in DataTransformerBase. This enables
transformers to report the mapping between transformed ordinals and
source ordinals, supporting use cases like computed columns which
return -1 to indicate no source ordinal.
- Add MapOrdinal(int, IDataReader) to IDataTransformer interface
- Add virtual MapOrdinal implementation in DataTransformerBase
- Add DataTransformerBaseTests with test for default behavior
Joseph Doherty