Composite key relational transformation breaking column sources

The composite key relational transformation hits key conflict as the same contribution is added for each relation for each column source.

This implementation is actually correct, the offending code is the Add call in the AdapterColumnSources which is missing logic that was not migrated in the 660 Rev ("IDB-231: Added support for multiple contributions to a transformation contribution.")

The rest of the changes in this revision need to be checked to confirm that they have been migrated.

Additionally, the UI has a bug in which a relationship that has already been added cannot be removed (the page just refreshes).