Add means of providing rejected records after close.

Some components, notably Snowflake, may provide rejected records after the close call. This is possible because the writes are handled asynchronously so it's not known if a record has been rejected until later. We do know about all of them after the close call.

This will require a change to DI code generation to call the method in WriterWithFeedback after the close (as well as after each write). It will also require the comments in WriterWithFeedback to change.