Update demand connection definition to work with pyomo framework

Update demand connection definition to work with pyomo framework

This feature would include updates to how the definition of control connections is done, building off of the demand component added in #328. This would adopt the paradigm where all technology components take in demanded load and output excess commodity.

The changes would mostly be around the inputs/outputs for the technology models, generalizing those, as well as simplifying the control connection definition to not require specification of specific demand in and excess out values.

Proposed solution

The changes in the input file would move from:

technology_interconnections: [
  ["ng_feedstock", "natural_gas_plant", "natural_gas", "pipe"], 
  ["solar","electrical_load_demand",["electricity_out","electricity_in"]], 
  ["electrical_load_demand", "natural_gas_plant", ["electricity_unmet_load", "electricity_demand"]], 
]

to something like:

technology_interconnections: [
  ["ng_feedstock", "natural_gas_plant", "natural_gas", "pipe"], 
]

control_connections: [
  ["electrical_load_demand", "solar"],
  ["solar", "natural_gas_plant"],
]

This would make the control connections more explicit, and support the pyomo dispatch optimization framework that is being developed.

Alternatives considered

Additional context