Handle modification of fair steps/workflows

[svenvanderburg]

• If step/workflow is unmodified (fetched from nanopub or published by user):
  • Extension should show that step is 'permanent'.
  • The cell should have green colour
• If step/workflow is modified
  • Extension should say: Derived from {source_uri}
  • And a 'revert' button should be there that reverts to the 'permanent' state
  • The cell should have a red colour
• If step/workflow is new and not published yet:
  • Extension should show: 'not published'
  • Button to publish cell
  • The cell should have yellow colour