Support Inside and hexbin

@ryanbaumann as discussed in email, need to support turf.inside and turf.hexbin in iOS.
per-email:
> iv. iOS - Turf.inside and Turf.hexbin are not yet supported. Please create an issue in this repo with your dev needs for hexbin and inside and tag

cc @julieemunro

Start by locating the existing Turf Swift APIs and how platform support is organized, then compare the expected behavior of turf.inside and turf.hexbin with the corresponding Turf.js functionality. Done means both capabilities are supported in iOS with behavior consistent with the project’s existing port.

Written by the indexing model from the issue text.