Changes to Get the customer-readable trace for a v2 conversation, nested Session→Turn→node→step

added the non-success response with the status 409

added the optional property session/items/observation_ids to the response with the 200 status

added the optional property session/items/truncation to the response with the 200 status

added the optional property turns/items/groups/items/steps/items/observation_ids to the response with the 200 status

added the optional property turns/items/groups/items/steps/items/truncation to the response with the 200 status

endpoint added