* to sessions in order to get details when running `autopilot list`
* to the autopilot rpc to be able to register features with privacy
flags via cli `autopilot add`
* to Features to know about default privacy flags in `autopilot features`
* to RegisterAutopilotSession in order to communicate to the autopilot
which privacy flags are being used after `autopilot add`
Update the Autopilot service AddAutopilotSessionRequest message to
include a new `group_id` field. Users may set this field to the ID of a
sessino group in order to link the new session to the older ones. The
Session message is also updated with new `group_id` field which will be
populated by the group a session.
