Implement parallel execution of the events

[arsho]

Add a scheduling component to coordinate parallel execution within the Drava runtime. The scheduler should manage task dispatch, concurrency control, and resource allocation across available execution units.

[perarnau]

We should figure out how XKRT allows for plugging a different scheduler to do that.

[rpereira-dev]

Entry point is here: https://github.com/rpereira-dev/xkrt/blob/26c5841a790e951e0f6af886e8d438ab1ca0df8a/src/task.cc#L579

Currently, assuming Drava only spawns independent tasks (aka embarrassingly parallel):

• If the workload is balanced, default-strategy results in round-robin between devices which will be fine.
• If not, then we could implement a load-balancing strategy using domain-specific knowledge within Drava -- XKRT tasks can be explicitly placed to a device