Since f35b59e a CLI poll reports trunk members as `3` with
trunk_group `Trk3`, but `show interfaces brief` has no line for Trk3
itself, so the trunk was missing from the interface list. The REST path
built that row on its own.
Both paths now use napalm_device_types.add_lag_interfaces, and the REST
path's copy is gone. One visible change there: `lag_members` is now in
port order (7, 10) instead of API order; the description already was.
The CLI path does not know the mode yet, so its trunks carry no
lag_mode. That needs `show trunks`, whose output is not at hand.
Needs napalm-device-types f3fa75b.
Closes#5