Define intervention policy

[YohannParis]

This is a back-end task to update the Intervention Java model into an InterventionPolicy Java model class as a TerariumAsset.

It should follow a structure ressembling the following:

// For example 
InterventionPolicy {
    modelId = UUID,
    interventions = [
        {
            name = "Start masking",
            appliedTo = "beta",
            statics = [
                { 
                    threshold: "2",
                    value: "0.0"
                },
                {
                    threshold: "10",
                    value: "0.2"
                }
            ],
            dynamics = [                
                { 
                    parameter: "infected_old",
                    threshold: "300",
                    value: "0.75"
                },
                { 
                    parameter: "infected_young",
                    threshold: "2",
                    value: "0.3"
                }
            ],
        },
    ]
}