Update Simulation.py to support multifeeder simulation

[afisher1]

To support Full DSO functionality the dataclass structure in Simulation.py must be updated to produce the following JSON structure:

{
    "power_system_configs": [
        {
            "SubGeographicalRegion_name": "Medium",
            "GeographicalRegion_name": "IEEE", 
            "Line_name": "C1C3E687-6FFD-C753-582B-632A27E28507",
            "simulator_config": {
                "simulator": "GridLAB-D",
                "simulation_output": {},
                "model_creation_config": {
                    "load_scaling_factor": 1.0,
                    "triplex": "y",
                    "encoding": "u",
                    "system_frequency": 60,
                    "voltage_multiplier": 1.0,
                    "power_unit_conversion": 1.0,
                    "unique_names": "y",
                    "z_fraction": 0.0,
                    "i_fraction": 1.0,
                    "p_fraction": 0.0,
                    "randomize_zipload_fractions": False,
                    "use_houses": False
                }
            }
        },
        {
            "SubGeographicalRegion_name": "Small",
            "GeographicalRegion_name": "IEEE",
            "Line_name": "49AD8E07-3BF9-A4E2-CB8F-C3722F837B62",
            "simulator_config": {
                "simulator": "GridLAB-D",
                "simulation_output": {},
                "model_creation_config": {
                    "load_scaling_factor": 1.0,
                    "triplex": "y",
                    "encoding": "u",
                    "system_frequency": 60,
                    "voltage_multiplier": 1.0,
                    "power_unit_conversion": 1.0,
                    "unique_names": "y",
                    "z_fraction": 0.0,
                    "i_fraction": 1.0,
                    "p_fraction": 0.0,
                    "randomize_zipload_fractions": False,
                    "use_houses": False
                }
            }
        }
    ],
    "simulation_config": {
        "duration": 7200,
        "start_time": 0,
        "run_realtime": True,
        "pause_after_measurements": False,
        "simulation_broker_port": 5570,
        "simulation_broker_location": "127.0.0.1",
        "simulation_name": "test-simulation"
    },
    "simulation_id": "simulation-id-12345"
}