[RFE] Support 802.3ad port groups on Cumulus devices

Since Yoga, multiple links in a port group are configured. This typically works for bond modes that do not require switch-side configuration, such as active/passive, TLB and ALB.

In some cases this may also work for 802.3ad link aggregates, if local_link_connection.port_id in the ports is set to the name of the port group interface. However some switches require different commands to be used when configuring port groups vs switch port interfaces. NVIDIA Cumulus switches require to use 'net add bond...' instead of 'net add interface ...'. Currently, if an 802.3ad port group is used on an NVIDIA Cumulus device, the switch will return an error (although the current error message regexes don't catch it, so binding is successful).