Description of problem:
Now when configuring subordinate ports of a main interface, linux-bridge, bond, ovs-bridge, ovs-bond, vrf are using 'port', but team use 'ports' as the property name. We'd better to unify them. For the backward compatibility, nmstate should allow the old name, but reports only one name.

Version-Release number of selected component (if applicable):
nmstate-0.4.1-1.el8.noarch

How reproducible:
100%

Steps to Reproduce:
1. Configure a team interface
2. nmstatectl show 
3. Check the team's property

Actual results:
interfaces:
- name: team0-0
  type: team
  state: up
  ipv4:
    enabled: false
    address: []
    dhcp: false
  ipv6:
    enabled: false
    address: []
    autoconf: false
    dhcp: false
  lldp:
    enabled: false
  mac-address: 9A:AE:EE:42:13:D5
  mtu: 1500
  team:
    ports: # the other types of main interface are using 'port'
    - name: dummy0-14
    - name: dummy0-15
    runner:
      name: roundrobin


Expected results:
Show text 'port' instead of 'ports'

Additional info: