Use Coroutine Decorator to make Helics Federate

[josephmckinsey]

The idea here is to create a decorator which applies to a coroutine, turning it into helics federate.

@helics_federate
@dynamic_input("voltage_in", Voltage)
@dynamic_output("voltage_out", Voltage)
@dynamic_input("topology", Topology)
@static_input("some_type", some_type)
async def state_estimator(time, voltage_in, voltage_out, topology, some_type):
    await time.request(1)
    voltage_arr = await voltage_in.get()
    await voltage_out.push(voltage_arr)

With this kind of language, we could be very compatible with mosaik and helics.

This might also allow us to create convenient subsystems like "race these two algorithms and then choose the output". That kind of behavior is hard to do with just HELICS.

It would also allow us to generate component descriptions very easily, and it would make real unit tests possible.