Don't hardcode service counts to check health

In core-network.py , the deploy() function takes a count argument giving the expected number of running services in "good health" condition:

    deploy(BASIC_W_NRF, 9)

This hand-coding of the count is error-prone, hard to maintain, and not friendly to user customization (e.g --type start-custom MYFILE.yaml).

Instead, it is possible to inspect the yaml file (with the python yaml module) to extract the (static) list of services it is supposed to launch, and then compare it with what's actually running:

import yaml
with open('docker-compose-basic-nrf.yaml') as f:
  data = yaml.load(f, Loader=yaml.FullLoader)
  print(data['services'].keys())

=>

dict_keys(['mysql', 'oai-udr', 'oai-udm', 'oai-ausf', 'oai-nrf', 'oai-amf', 'oai-smf', 'oai-spgwu', 'oai-ext-dn'])

$ docker-compose -f docker-compose-basic-nrf.yaml ps -a | fgrep '(healthy)'
mysql               "docker-entrypoint.s…"   mysql               running (healthy)   3306/tcp, 33060/tcp
oai-amf             "/bin/bash /openair-…"   oai-amf             running (healthy)   80/tcp, 9090/tcp, 38412/sctp
oai-ausf            "/bin/bash /openair-…"   oai-ausf            running (healthy)   80/tcp
oai-ext-dn          "/bin/bash -c ' ip r…"   oai-ext-dn          running (healthy)   
oai-nrf             "/bin/bash /openair-…"   oai-nrf             running (healthy)   80/tcp, 9090/tcp
oai-smf             "/bin/bash /openair-…"   oai-smf             running (healthy)   80/tcp, 8080/tcp, 8805/udp
oai-spgwu           "/bin/bash /openair-…"   oai-spgwu           running (healthy)   2152/udp, 8805/udp
oai-udm             "/bin/bash /openair-…"   oai-udm             running (healthy)   80/tcp
oai-udr             "/bin/bash /openair-…"   oai-udr             running (healthy)   80/tcp