BUG: Save a cached copy of the representation to compare against

A cached copy of the representation data is stored and the is compared against
when setting a new representation.
This fixes issue 14558(http://www.paraview.org/Bug/view.php?id=14558).

Change-Id: Id5509f6ecd27cd74f52bb4365756ad375dce3409
Merge topic '14558-disconnect-cleanup' into next

b6b953a8 BUG: Save a cached copy of the representation to compare against