Feature/bulk merge

[kwahlin]

I think we can merge this now. Should be fairly easy to just replace the part where we emulate the changes (

librisxl/rest/src/main/groovy/whelk/rest/api/BulkChangePreviewAPI.java

Line 62 in 72e410f

// TODO: Fetch ready-made changes

) with the results of a dry-run once we have that in place.

TODO:

• Address this:

  librisxl/whelktool/src/main/resources/bulk-change-scripts/merge.groovy

  Line 16 in 72e410f

  // TODO: What if there are links to a record uri?

  
  I don't think we should replace links to record uris with links to thing uri so the question is what to do with them (if they ever appear)?
• Would be nice to make the frontend preview aware of and able to display different types of changes depending on the change sets content.

[olovy]

I think that there is now a bit of unclear division of responsibility between the different Specification classes and the corresponding whelktool scripts. But that will hopefully be fixed when we use recorded dry-runs for previews.