Arrange for agccActor to call `gen2 updateTelStatus` for each exposure

We need to trigger updates of the telescope tables and MHS keywords for each agc exposure. That is done by commanding gen2Actor with `gen2 updateTelStatus caller=agcc` to record the latest gen2 status information.

For an example, see mcsActor's McsCmd.py:getNextFileIds, but we need to handle subvisits differently.