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

Updates graph build API endpoint - timestamps are now passed in the JSON body and not in the URL query string

Moves SDN controller and SFEMC port numbers out of implementation - passed to CLMC as environment variables, default 8080 port used if not passed

Modified the build_network_graph API endpoint to read the sr-cluster mappings from a file - temporary solution

Added a function to generate the network topology given the switch-to-switch links, switch IP addresses and cluster-to-router mapping; changed ComputeNode to Cluster; added Switch nodes; modified tests