Modifies graph API to not start graph monitoring process if no UserEquipment nodes are found in the graph

Fixes bug with empty list of endpoints in the graph pipeline script

See merge request FLAME/consortium/3rdparties/flame-clmc!55

Upgrading CLMC to latest version

See merge request FLAME/consortium/3rdparties/flame-clmc!52

Implements a DELETE API endpoint for stopping a graph monitoring process and refactors the graph API tests

Updates graph_monitor API endpoint to also save the request identifier and the pipeline process identifier

Implements and tests an addition to the response of the build request for a temporal graph - now the list of endpoints is also returned

Adds API endpoint to continuously execute the graph workflow - implements error handling functionality only

Refactors tests for handling invalid requests and adds new tests for the execute pipeline API endpoint