Error message for unknown key only mentions metadata filter keys

[chaoran-chen]

Calling /sample/aggregated?doesNotExist=123 returns the error:

{
    "error":
    {
        "type": "about:blank",
        "title": "Bad Request",
        "status": 400,
        "detail": "'doesNotExist' is not a valid sequence filter key. Valid keys are: <many keys>"
    },
    "info":
    {
        "dataVersion": null,
        "requestId": "6be22ccd-edd5-4b92-bcfa-f458de150de3"
    }
}

<many keys> only contains the keys for filtering the metadata. It misses

• Mutation filters (e.g., nucleotideMutations)
• fields
• OrderBy and limit
• more?