can't filter by object_type=device in auditlogs

Although the filtering by object_id works fine with a device id, filtering by object_type does not.

So far this does not appear to be supported by the API (https://github.com/mendersoftware/auditlogs/blob/master/docs/management_api.yml#L87-L94), but I would expect it to be to support listing the remote terminal sessions.