feat: added s_dwithin predicate

[jkaniuka]

Adds support for s_dwithin predicate to query GeoJSON records whose feature.geometry is within a given distance from a specified point.

Here ➡️ pygeoapi/pull/2403 is a link to corresponding PR that modifies the Mongo provider in pygeoapi. Our goal is to enable queries like the one below:

{
    "filter-lang": "cql2-json",
    "filter": {
        "op": "s_dwithin",
        "args": [
            {"property": "feature.geometry"},
            {
                "type": "Point",
                "coordinates": [13.0, 65.0]
            },
            250000,
            "meters"
        ]
    }
}

Thanks to @Jacob7052 for the implementation 😎