Dispose experiment/trace back-end resources when closing an experiment from the UI

[bhufmann]

The TSP allows to open traces and experiments on the server back-end. However, there is now dedicated request available to dispose the back-end resources related to experiments and traces in the back-end. There should be a TSP request to trigger the disposal of resources in the back-end when the front-end close the experiment.

Consider the following API: PUT /experiments/{expUUID}:close

Consider other alternatives before implement this API.