Remove cut link 11882 (rebased onto dev_5_0)



This is the same as gh-1960 but rebased onto dev_5_0.

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This addresses https://trac.openmicroscopy.org.uk/ome/ticket/11882 and https://trac.openmicroscopy.org.uk/ome/ticket/11881. Web Cut, Copy & Paste of P/D/I & S/P should behave the same as Insight.

To test:
 - "Cut Link" an Image or Dataset - should remove it from parent (become orphan).
 - "Paste Link" should paste it into new parent.
 - "Copy Link" and "Paste Link" should behave as normal.

 - Try various copy, cut & paste actions to see if the Tree behaves in a logical way - Compare to how Insight behaves.