Have mcsActor request telescope status updates for each subvisit exposure.

When a new visit is fetched, the gen2Actor updates the tel_status and obs_conditions opdb tables and generates MHS keywords for the headers and for any further calculations (PA, M2 piston, altitude, temperature, etc).

For subsequent exposures within a visit (i.e. for the convergence steps), the actor needs to request updates directly, by sending gen2 updateTelStatus caller=mcs just before the exposure is actually taken. Do so.