Initial NaC Controller implementation

This implementation must offer:

• a REST API built on user-provided Nokia's Network-as-Code (Nac) library, exposing available resources
• a controller that:
  • synchronizes with the NaC REST API and creates the respective Resource Specifications and Resources in OpenSlice Resource Catalog & Inventory
  • connects to the OpenSlice message bus and subscribes to events based on NaC Resource Specifications. When a service orchestration involves NaC Resource Specifications, the controller forwards the requests to the REST API and the NaC, respectively