Remove the plotResult method from the DSE backend API
Current status
The method was used to display / select results from the DSE backend. This part is now only used for debugging internals, while the main functionality went to the common visualization.
Change Request
Remove the API definition and the (now empty) implementations as this functionality is unused.
(from redmine: issue id 3599, created on 2018-12-19, closed on 2019-09-30)