Implement asynchronous scheduler
this adapts the scheduler implementation to the IQueueingEventProcessor interface, which can asynchronously schedule events, a requirement stated by @frankm to be able to run it online.
For details about the interface, see gaudi/Gaudi!966 (merged).
The performance doesn't suffer, if anything it gets better (@clemenci made the tests there)
TLDR: much benefit, no cost.
Edited by Rosen Matev