TurfMisc#nearestPointOnLine does not report distance along the route

Capturing from https://turfjs.org/docs/#nearestPointOnLine, the Feature returned from TurfMisc#nearestPointOnLine should return a location number property that describes the distance along the route of the computed intersection point, next to already available dist number property which describes the distance to the original point. Also would be great to explain those properties in the Javadoc and add public constant instead of relying on raw strings for dist and location.

/cc @cafesilencio

TurfMisc#nearestPointOnLine から始め、返される Feature を turfjs.org/docs/ の nearestPointOnLine のドキュメントと比較します。結果にルート距離の location プロパティが含まれ、dist/location プロパティが Javadoc で説明され、raw string が public 定数に置き換えられていれば作業は完了です。