Sim API Consistency: Object Creation

[Starlight220]

Each sim class should have three parameter options to create objects:

• a real hardware object
• a port/index/channel number
• a native handle (maybe not expose this?)

SimDeviceSim is a bit different since (1) doesn't make much sense, and (2) uses a string key.

Other than ensuring that everything has all three, we also need to standardize what is a constructor and what is a factory method.
Currently, we have some of each.
I'm of the opinion that everything should be constructors. @PeterJohnson -what about you?

Having this consistent will really help wpilibsuite/frc-docs#1077.

[PeterJohnson]

We can't always use constructors because we can't always discriminate on type. Take a look at DutyCycleSim for example. We want to be able to construct it from:

• a DutyCycle object
• a DigitalInput channel number
• a DutyCycle FPGA index number

The last two are both integers, so we use factory functions for those, but a constructor for the first one.

In many other places we don't have this confusion (e.g. AnalogInputSim) so we just use constructors rather than forcing the use of factory functions.