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

Fixes a bug in the graph network measurements generator script and adjusts the static network config

Updates CLMC to always set the HTTP Accept header to application/json - otherwise, error messages might be sent as HTML

Updates alerts API to use new line character concatenation and hash values, updates tests to reflect on this, implements and tests validation against TOSCA resource spec.