Ipam service

I think the main functionality regarding the ipam service (NAT-152) is implemented so I'm sending the PR. Since the last call, I added support for list of containers per service, support for extattrs, and added an endpoint to get status and usage fields of hosts in a network.

The service is implemented in this directory: https://gitlab.geant.org/goat/gap/geant-service-orchestrator/-/tree/ipam-service/gso/services

A configuration file is needed based on this template exported as OSS_PARAMS_FILENAME: https://gitlab.geant.org/goat/gap/geant-service-orchestrator/-/blob/ipam-service/gso/oss-params-example.json

There is still some polishing to do regarding error checking/propagation and how to expose some functionality to WFO (if needed) such as constraints for extensible atributes, different modes for allocating things, host/network deletion, etc. but maybe it's better to tinker with the IPAM service from WFO to see how to handle these things according to the workflows.

I kept a dummy menu in _ipam.py and a dummy entry point in ipam.py that are useful for testing. Can be deleted later.

gso/services/_ipam.py

 import ipaddress
-import json
 import requests
 from enum import Enum
 from pydantic import BaseSettings
@@ -439,7 +438,7 @@ def allocate_service_host(hostname=None,
 Below methods are not used for supported outside calls
 """
 
-
+'''
 def _find_containers(network=None, ip_version=4):
     """
     If network is not None, find that container.
@@ -588,8 +587,8 @@ def _get_network_usage_status(network):
     assert r.status_code >= 200 and r.status_code < 300, \
         f"HTTP error {r.status_code}: {r.reason}\n\n{r.text}"
     return r.json()
-
-
+'''
+'''
 if __name__ == '__main__':
     while True:
         print("1. Find all containers")
@@ -679,3 +678,4 @@ if __name__ == '__main__':
 
         else:
             print("Invalid choice. Please try again.")
+'''