Improve NearestPoint type for @turf/nearest-point so that it keeps the properties of the points in the FeatureCollection

[EmilJunker]

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This PR improves the NearestPoint type and the type definition for the nearestPoint function.

Consider the following example in TypeScript:

const coordinatesList = [[0, 0], [1, 1], [0, 1]];
const pointsList = coordinatesList.map((coordinate, i) => {
    return turf.point(coordinate, {
        name: `point${i}`
    });
});
const pointsCollection = turf.featureCollection(pointsList);
const myNearestPoint = turf.nearestPoint(turf.point([2, 2]), pointsCollection);

With the old behaviour myNearestPoint.properties.name is of type any according to TypeScript.

With the changes in this PR, the type of myNearestPoint.properties.name is correctly inferred as string.

This change should be non-breaking.