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

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