Determine if we should remove `Linked*` types from public API

[ajfriend]

This section was previously in the naming RFC, but we will move it to a separate discussion.

Here's the previous section:

Polygons

Data Structures

• remove the LinkedGeoCoord, LinkedGeoLoop, and LinkedGeoPolygon from the public API and only use them internally
• expose GeoMultiPolygon instead of LinkedGeoPolygon
  • GeoMultiPolygon is easier for clients to work with
• rename GeoBoundary to CellBoundary to indicate it is space-limited to describing the geometry of cells

Current name	Proposed name	Notes
GeoBoundary	CellBoundary	<= 10 stack-allocated GeoPoints
.
GeoCoord	GeoPoint
Geofence	GeoLoop	heap-allocated GeoPoints
GeoPolygon	GeoPolygon
GeoMultiPolygon	GeoMultiPolygon	replaces LinkedGeoPolygon in public API
.
LinkedGeoCoord	LinkedGeoPoint	(remove from public API)
LinkedGeoLoop		(remove from public API)
LinkedGeoPolygon		(remove from public API)
.
CoordIJ	same

Functions

Current name	Proposed name	Notes
h3ToGeoBoundary	cellToBoundary	returns CellBoundary
DNE	cellToLoop	returns GeoLoop
DNE	loopToBoundary
DNE	boundaryToLoop
getH3UnidirectionalEdgeBoundary	directedEdgeToBoundary	returns CellBoundary
.
polyfill	same, polygonToCells	takes GeoPolygon
DNE	multiPolygonToCells	takes GeoMultiPolygon
h3SetToLinkedGeo	cellsToMultiPolygon	returns GeoMultiPolygon

[ajfriend]

The plan is to benchmark GeoMultiPolygon versions of these functions against the existing LinkedGeoPolygon functions to see if the overhead of converting to GeoMultiPolygon is significant.

[ajfriend]

#308