Add `ChallengeSummary` to Swagger

[tordans]

The API endpoint https://maproulette.org/api/v2/data/challenge/38309?includeByPriority=false is not documented in the Swagger Docs at https://maproulette.org/docs/swagger-ui/index.html#/

I found some hints on how to authenticate in https://github.com/maproulette/maproulette-backend/blob/main/postman/maproulette2.postman_collection.json#L4776-L4811

It provides a response like

[
    {
        "id": 38309,
        "name": "Missing buildings - Scotland",
        "actions": {
            "total": 8608,
            "available": 4021,
            "fixed": 2941,
            "falsePositive": 266,
            "skipped": 30,
            "deleted": 0,
            "alreadyFixed": 1325,
            "tooHard": 25,
            "answered": 0,
            "validated": 0,
            "disabled": 0,
            "avgTimeSpent": -451551,
            "tasksWithTime": 4587
        }
    }
]

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Another thing is, that IMO this API endpoint should not require an authentication. Other endpoints like the general challenge info do not require authentication. But unfortunately that only includes very basic data on the completion state.