Dynamic bounding box when supplied a coordinate

Nobody has claimed this yet.

I thought this would be a really interesting feature if possible. Create a new initializer `TerrainNode(lat: , lon: )` that would take a coordinate and dynamically calculate the bounding box for you. It would use [feature querying](https://www.mapbox.com/help/define-feature-querying/) to check and see if the coordinate was a place in the city, natural park, etc. If it was in the city, the user is likely looking at a couple buildings and therefore the bounding box should presumably be small. However, if the feature is like a natural park they are likely looking at terrain and would want an understandably bigger bounding box.

It's a very preliminary idea but it would be very interesting if it could be implemented. I've noticed myself that different types of features require different bounding box sizes.

The issue names no files or tests; start by locating TerrainNode and reviewing the linked feature-querying documentation. Define how queried feature types map to bounding-box sizes, then verify that TerrainNode(lat:lon:) produces the intended bounds for city and natural-park features.

Written by the indexing model from the issue text.