New Experiment abrupt4xCO2

[github-actions]

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Adding the following new data.

{
    "id": "abrupt4xco2",
    "type": [
        "wcrp:experiment",
        "cmip7"
    ],
    "activity": [
        "HighResMIP2"
    ],
    "description": "A coupled experiment with abrupt 4xCO2 forcing, starting from the end of the spinup-1950 simulation, enforces an instantaneous 4xCO2 increase  References: Roberts, M. J., Reed, K. A., Bao, Q., Barsugli, J. J., Camargo, S. J., Caron, L. P., \u2026 & Zhao, M. (2025). High-Resolution Model Intercomparison Project Phase 2 (HighResMIP2) towards CMIP7. Geoscientific Model Development, 18, 1307\u20131332  [High-Resolution Model Intercomparison Project Phase 2 (HighResMIP2) towards CMIP7.pdf](https://github.com/user-attachments/files/19402163/High-Resolution.Model.Intercomparison.Project.Phase.2.HighResMIP2.towards.CMIP7.pdf)  Webpage: https://highresmip.org/experiments/experiment_cmip7/",
    "label": "abrupt4xCO2",
    "long-label": "Idealised experiments for CMIP-comparable metrics - abrupt 4xCO2 starting form the end of spinup-1950",
    "minimum-number-of-years": "30",
    "model-realms": [
        {
            "id": "aogcm",
            "is-required": true
        },
        {
            "id": "aer",
            "is-required": false
        },
        {
            "id": "bgc",
            "is-required": false
        },
        {
            "id": "chem",
            "is-required": false
        }
    ],
    "parent-experiment": [
        "none"
    ],
    "start-date": "1950-01-01",
    "sub-experiment": "none",
    "tier": "3"
}

Resolves #83

[wolfiex]

Updated to #114