Add Turf buffer method

Nobody has claimed this yet.

Turf.js has a [`Turf#buffer`](http://turfjs.org/docs/#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](https://github.com/locationtech/jts) to get the job done. We need to look into this a bit further / discuss if that makes sense.

cc @osana @kevinkreiser

Start by reviewing Turf#buffer and the linked LocationTech JTS library to understand the required geometry behavior and whether it can be used from this Java SDK. Then identify the appropriate SDK entry point for a buffer method and discuss the dependency and API choices with maintainers. Done means the project has an agreed implementation path for defining buffered offline map regions.

Written by the indexing model from the issue text.