Add more config options to HELICS

[josephmckinsey]

In order to run multiple and hierarchical simulations, additional brokers must be started, and federates must be pointed towards these brokers.

The "proper" way to initialize this would be to pass a partial JSON config in the style of a HELICS federate JSON. Word of mouth from a HELICS developer has indicated that we should be able to just pass this partial config in. Since we do a significant amount of channel name reconfiguration, algorithm developers will still need to define their own publications and subscriptions.

Key properties for nice configuration:

• name
• broker_address
• broker_port
• core_type (not as required)