WIP: Add RAVENS schema

[juanjospina]

This is is still a Work in Progress (WIP) branch.

The parser can be (temporary) tested using the following:

pmd_file = "../file.json"

# parse JSON file
pmd_data = parse_file(pmd_file)

# instantiate model
pmd_model = instantiate_mc_model_ravens(pmd_data, ACPUPowerModel, build_mc_opf)

result = optimize_model!(
        pmd_model,
        relax_integrality=false,
        optimizer=ipopt,
        solution_processors=Function[]
    )