Add new companion helper methods to interfaces.

[igo95862]

Look through interfaces where the new settings helper can be applied.

[igo95862]

Possible helper locations:

• interfaces_devices.py
  • NetworkManagerDeviceWifiP2PInterfaceAsync
    • ~start_find~ unrelated
  • NetworkManagerDeviceWirelessInterfaceAsync
    • ~request_scan~ unrelated
  • NetworkManagerDeviceInterfaceAsync
    • ~reapply~ implemented
    • ~get_applied_connection~ implemented
  • NetworkManagerPPPInterfaceAsync
    • ~set_ip4_config~ unrelated
    • ~set_ip6_config~ unrelated
• interfaces_other.py
  • NetworkManagerDHCP4ConfigInterfaceAsync
    • ~options~ unrelated
  • NetworkManagerDHCP6ConfigInterfaceAsync
    • ~options~ unrelated
  • NetworkManagerIP4ConfigInterfaceAsync
    • ~address_data~ unrelated
    • ~route_data~ unrelated
    • ~nameserver_data~ unrelated
  • NetworkManagerIP4ConfigInterfaceAsync
    • ~address_data~ unrelated
    • ~route_data~ unrelated
    • ~nameserver_data~ unrelated
  • NetworkManagerSettingsConnectionInterfaceAsync
    • ~update~ implemented
    • ~get_settings~ implemented
    • ~update2~ implemented
  • NetworkManagerSettingsInterfaceAsync
    • ~add_connection~ implemented
    • ~add_connection_unsaved~ implemented
    • ~add_connection2~ implemented
  • NetworkManagerVPNPluginInterfaceAsync
    • ~connect~ unrelated
    • ~connect_interactive~ unrelated
    • ~need_secrets~ unrelated
    • ~set_config~ unrelated
    • ~set_ip4_config~ unrelated
    • ~set_ip6_config~ unrelated
    • ~new_secrets~ unrelated
  • NetworkManagerInterfaceAsync
    • ~add_and_activate_connection~ implemented
    • ~add_and_activate_connection2~ implemented

[igo95862]

Probably want to add secrets fetching feature for helpers: #43