SchedulerSvc: query event for a given slot

For the AvalancheSchedulerSvc we would like to know which Event(Context) is currently executing in a given slot. It would seems like a natural question to ask, but unless I am missing it, we don't seem to have any way to retrieve this information.

Essentially exposing (a reduced version) of the scheduler's:

std::vector<EventSlot> m_eventSlots;

Or is there already a way of doing this? cc @leggett @bwynne @clemenci