Creates a device location observation. Note that creating a location observation will trigger the associated device's last known location. When creating a device location observation, you may set `device_id` to either the system id or the device's unique id. If you use the device's unique id you must also specify the device's company in the `company_id` field so that the system can uniquely identify the device. After creation, `device_id` will always contain the device's system id.