Add ExplodeList action

This provides a new action to explode a string into an array with a configurable separator.

I'm not sure about the output data type being String when it is actually an array. It seems to work, however:

{
    "input": {
        "input_1": "foo,bar,baz"
    },
    "action": [
        {
            "action": "Explode Comma separated list",
            "output": {
                "value": [
                    "foo",
                    "bar",
                    "baz"
                ]
            }
        }
    ]
}