VPN steps refactor + libreswan 4 fixes

@RunTests:vpn_describe,multiple_vpn_connections,vpn_keep_username_from_data,vpn_list_args,iptunnel_create_modify,iptunnel_restart,iptunnel_ip6gre_create_device,wireguard_activate_connection,openvpn_ipv4,openvpn_ipv4_neverdefault,openvpn_ipv6,openvpn_ipv6_neverdefault,openvpn_set_mtu,openvpn_set_firewall_zone,openvpn_terminate,openvpn_delete_active_connection,openvpn_persist,vpnc_add_profile,pptp_add_profile,pptp_passwd_file,pptp_terminate,libreswan_ikev1_aggressive,libreswan_ikev1_main,libreswan_ikev2,libreswan_add_profile_wrong_password,libreswan_terminate,libreswan_delete_active_profile,libreswan_dns,libreswan_start_as_secondary,libreswan_connection_renewal,libreswan_provides_and_obsoletes,libreswan_import,libreswan_export,libreswan_autocompletion,libreswan_activate_asking_for_password,libreswan_activate_asking_for_password_with_delay,libreswan_activate_asking_for_password_and_secret,libreswan_reimport,libreswan_reimport_ikev2,libreswan_configurable_options_reimport,strongswan_add_profile,strongswan_connection_renewal,strongswan_terminate,strongswan_delete_active_profile,strongswan_dns,strongswan_start_as_secondary,update_firewall_zone_upon_reconnect,pppoe_and_ethernet_together,connect_to_pppoe_via_pap,connect_to_pppoe_via_chap,disconnect_from_pppoe,pppoe_over_vlan