Add Turf buffer method

Turf.js has a Turf#buffer method that would be useful for defining offline map regions. An example use case in navigation would be defining a buffer around a route geometry for an offline download:

@zugaldia mentioned that this may not be a straightforward port to java, possibly necessitating bringing in a third party library to get the job done. We need to look into this a bit further / discuss if that makes sense.

cc @osana @kevinkreiser

先檢視 Turf#buffer 和相關的 LocationTech JTS 函式庫，以了解所需的幾何行為，以及是否能從這個 Java SDK 使用它。接著找出適用於 buffer 方法的 SDK 入口點，並與維護者討論相依性和 API 的選擇。當專案對定義具有緩衝區的離線地圖區域之實作途徑達成共識時，即表示完成。